The visit from Workers Party Vice-Chairman Ri Su-yong is being seen as an attempt by the two countries to patch up their relationship.
It has been strained by North Korea's recent military activity.
Mr Ri also delivered a message from leader Kim Jong-un saying the North would not end its nuclear programme.
North Korea's KCNA state news agency reported that Mr Kim had vowed to continue with his policy of economic progress alongside nuclear development.
China's Xinhua state news agency made no mention of the nuclear comments, but said Mr Kim hoped to build closer ties with China.
It quoted Mr Xi repeating China's policy on the Korean peninsula, calling for calm and restraint, increased communication and regional stability.
Mr Ri's visit to China is the first by a North Korean official since a once-in-a-generation Workers Party Congress last month.
The former foreign minister was expected to brief Mr Xi on any major developments at the congress.
China remains an ally of North Korea's while at the same time abiding by sanctions imposed by the UN over its repeated missile launches and a nuclear test earlier this year.
Beijing appears to have been growing impatient in recent years with the reclusive state, which is dependent on trade with China.
China's President Xi Jinping has stressed the importance of "friendly" ties with North Korea, during a visit by a high-ranking Pyongyang official.