The meeting is expected to re-elect leader Kim Jong-il to his most important post - chairman of the powerful National Defence Commission - and strengthen his grip on power, despite recent health concerns.
Analysts say the timing of the rocket launch, the rally and recent footage of Mr Kim have all been designed to bolster support ahead of the meeting.
Senior communist party secretary Choe Thae-Bok called the launch a "proud victory".
"The imperialists and reactionaries who have committed all kinds of despicable acts, tenaciously pursuing... moves to isolate and stifle us, will be driven into a yet tighter corner because of our satellite launch," he told the rally.
The North insists it put a communications satellite into orbit, which is beaming back patriotic songs. On Tuesday, it released what it said was a video recording of the launch.
But South Korea, Japan and the US say there is no sign of the satellite in space. They say it crashed back down to Earth, into the Pacific Ocean.
The UN Security Council has been debating whether North Korea should be punished for the weekend's launch.
The US, South Korea and Japan say the launch violates UN Security Council Resolution 1718, which was adopted in October 2006 and bans North Korea from carrying out ballistic missile activity.
Japan and the US are pushing for a UN Security Council resolution which would reinforce and possibly extend the existing sanctions against North Korea, applied in the wake of the country's nuclear test in 2006.
But China and Russia have been more cautious, saying they are yet to be convinced Pyongyang broke the rules.
Moscow said Sunday's test was a cause for concern but urged against "hasty conclusions" while China said Pyongyang had the right to a peaceful space programme.
North Korea's deputy UN ambassador Pak Tok-hun has warned the council against trying to punish Pyongyang.
If the 15-member security council took "any kind of steps whatever, we will consider this infringes upon the sovereignty of our country", he said, threatening "necessary and strong steps".
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