New Zealand 31 (13)
Tries: Nonu, Muliaina, Ranger, Dagg Cons: Carter Pens: Carter 2, Weepu
South Africa 17 (7)
Tries: Rossouw, Burger Cons: Steyn 2 Pens: Steyn
Mils Muliaina scored New Zealand's second try after just 12 minutes
New Zealand proved too strong for South Africa to claim their second win over the world champions in seven days and take early command of the Tri-Nations.
The All Blacks had swept past the Springboks 32-12 in last week's opening match, and they were the better side once again in a windy Wellington.
Despite a poor kicking day for Dan Carter, four tries were enough to see off largely unthreatening opposition.
Australia host the Springboks in next Saturday's third Tri-Nations match.
"We were prepared to play rugby from a fair way out from the goal line and were prepared to attack from our own half and that resulted in a couple of tries," said New Zealand coach Graham Henry.
"The new interpretation of the tackle law has changed the game a lot. It allows you to get continuity of possession and to build to score points and the guys did that exceptionally well."
We held it in there but they just kept coming, kept getting quick ball and kept stumping up
Springboks captain John Smit
There had been plenty of talk in the build-up to suggest that South Africa were not about to be rolled over as comprehensively as they had been in Auckland, but they made a dreadful start.
Danie Rossouw had come in for Bakkies Botha, who was banned for nine weeks for head-butting Cowan in the opening match, but Rossouw was sent to the sin bin as early as the fourth minute.
The lock was judged to have provoked an altercation with All Blacks captain Richie McCaw, and while it might have been harsh the home side showed little sympathy.
Dan Carter missed an early shot at goal but moments later Ma'a Nonu was driven over the line after a powerful passage of New Zealand play, and when Muliaina raced clear from halfway to score a second try after just 12 minutes, a rout looked to be on the cards.
The Springboks did manage to steady matters but showed little threat before Carter finally landed his first kick of the day, with his fourth attempt, to make it 13-0 after half an hour.
South Africa needed inspiration and it came from scrum-half Ricky Januarie, who broke the All Blacks line off the back of a line-out and provided the momentum that allowed Rossouw to go over from close range.
Morne Steyn slotted the conversion and, despite having been outplayed for much of the half, the visitors went in at the break trailing just 13-7 after Carter missed yet another penalty chance.
A penalty against McCaw allowed Steyn to bring South Africa within three points early in the second half and a real contest appeared to be brewing, only for New Zealand to reassert their authority in superb style.
A Carter up-and-under caused confusion in the South Africa midfield and the ball found its way out wide to Rene Ranger, who did brilliantly to stay in-field and touch down in the corner.
The wind was playing havoc with Carter's place-kicking and he missed the conversion, prompting the unusual move of replacing the star fly-half for the next penalty chance, which Piri Weepu calmly sent over to make it 21-10.
McCaw appeared fortunate to avoid a yellow card on the hour mark for an infringement in a ruck, and he immediately played a key role in turning over possession as the Springboks threatened the line.
All Blacks substitute Israel Dagg made a major impact, and put the result beyond doubt, with a fine solo score in the corner on 64 minutes and Carter finally got his kicking game back on track with the conversion and a penalty.
Schalk Burger reduced the deficit with a late try, converted by Steyn, but it was little comfort in a comprehensive defeat and South Africa will be glad to see the back of the All Blacks as they head to Brisbane.
"I'm obviously surprised to get a yellow card at the start of the Test match because it does put us on the back foot," said Springboks captain John Smit.
"We had a chance with Dan (Carter) missing all those early kicks and it made the deficit only 10 points, which is an easy target.
"We held it in there but they just kept coming, kept getting quick ball and kept stumping up."
New Zealand: Mils Muliaina; Cory Jane, Conrad Smith, Ma'a Nonu, Rene Ranger, Daniel Carter, Piri Weepu; Tony Woodcock, Keven Mealamu, Owen Franks, Brad Thorn, Tom Donnelly, Jerome Kaino, Richie McCaw, Kieran Read.
Replacements: Corey Flynn, Ben Franks, Sam Whitelock, Liam Messam, Jimmy Cowan, Aaron Cruden, Israel Dagg.
South Africa: Zane Kirchner, Jean de Villiers, Jaque Fourie, Wynand Olivier, Bryan Habana, Morne Steyn, Ricky Januarie; Gurthro Steenkamp, John Smit, CJ van der Linde, Danie Rossouw, Victor Matfield, Schalk Burger, Francois Louw, Pierre Spies.
Replacements: Chiliboy Ralepelle, BJ Botha, Andries Bekker, Ryan Kankowski, Ruan Pienaar, Butch James, Gio Aplon.
Sin-bin: Rossouw (4)