It is Premier Kim Yong-il's first visit to China since taking office in 2007
China says it is concerned by growing tensions on the Korean peninsula over North Korea's planned rocket launch.
North Korea's premier is in Beijing for talks with Chinese President Hu Jintao and Premier Wen Jiabao - with the test-fire expected to top the agenda.
South Korea and the US say Pyongyang may be preparing to test-fire a long-range missile and have warned it against the launch planned for April.
The North insists it is preparing to send up a communications satellite.
North Korea is banned from firing either device under a UN Security Council resolution prohibiting it from ballistic activity.
Pyongyang has said the launch will take place between 4-8 April, and that any attempt to shoot it down would result in war.
Earlier this month Japan suggested it could deploy a vessel equipped with missile interceptor technology to the Sea of Japan (East Sea) to destroy the rocket.
North Korean Premier Kim Yong-il - who is not related to leader Kim Jong-il - arrived in Beijing on Tuesday for a five-day trip.
China - one of Pyongyang's closest allies - has avoided directly criticising the rocket launch.
Foreign Ministry spokesman Qin Gang said: "At present, the situation on the Korean peninsula is rather complicated with an increasing number of uncertain factors.
"We express concern over this."
During the visit, Beijing is also expected to encourage the North to restart stalled six-nation talks on ending North Korea's nuclear programme.
Beijing said earlier this month that "safeguarding peace and stability on the Korean peninsula serves the interests of all relevant parties".
The two communist states are to hold a ceremony marking 60 years of diplomatic relations.
Ahead of his visit, Mr Kim described China as a bulwark of regional stability.
North Korea's planned launch is stoking already heightened tensions with South Korea.
Pyongyang recently put its military on full combat alert, and shut its border with the South, in what it said was retaliation for the recent annual military exercise by US and South Korean forces.
In January, the North scrapped a series of peace agreements with the South over Seoul's decision to link bilateral aid to progress on denuclearisation.