Fidel Castro appeared frail and gaunt during his meeting with Mr Hu
China's President Hu Jintao has signed a series of trade and investment accords with Communist ally Cuba during a landmark visit to the island.
President Hu agreed to continue buying nickel and sugar from Cuba and to send food aid to the island, Cuban TV said.
The visit is part of Mr Hu's tour of Latin America, where he is seeking to boost economic ties with the region.
Mr Hu also met Cuba's ailing former leader Fidel Castro, who has not been seen in public since 2006.
"I see in person that you have recovered and have been energetic so I feel very pleased," Mr Hu was quoted as telling Mr Castro, 82, who underwent emergency surgery two years ago.
Cuban TV showed a picture of the two men, in which Fidel Castro looked gaunt and frail.
This visit, Mr Hu's first since 2004, saw the two nations sign agreements boosting trade and investment with Cuba which is struggling to recover from three devastating hurricanes.
Cuban President Raul Castro, who officially succeeded his brother in February, greeted his Chinese counterpart at Havana's Palace of the Revolution.
The two leaders also visited some of the 1,000 Chinese students who are learning Spanish in Cuba.
At one point Mr Castro burst into song, singing in Chinese of the praises of their former revolutionary leader Chairman Mao Zedong which he said he learned while travelling in 1953.
"I don't have the memory that Fidel has but I remember that song," he said.
China is now Cuba's biggest trading partner after Venezuela, with bilateral trade at $2.3bn (£1.5bn) in 2007.
Across Latin America, China has seen its trade climb from $13bn in 2000 to more than $100bn in 2007.
"My visit is aimed at increasing friendship and co-operation between our two nations, and working together with our Cuban comrades to build a promising future," Mr Hu said.
As well as trade deals, Mr Hu formally extended the second $70m phase of a $350m credit package designed to repair and renovate Cuban hospitals.
Throughout the Cold War Cuba was traditionally a much firmer ally of the Soviet Union than China, but that changed when the Soviet Union collapsed in 1991, leaving Cuba almost bankrupt, says the BBC's Michael Voss in Havana.
Mr Hu arrived in Cuba from Costa Rica, where he also signed co-operation agreements.
President Hu last visited Cuba in 2004 when Fidel Castro was still in charge
He will travel on from Cuba to Peru where he will attend the Apec (Asia-Pacific Economic Co-operation) summit in Lima on 21 and 22 November.
But China is not the only power interested in securing greater access to Latin American raw materials and other resources.
President Hu will be followed next week by Russian President Dmitry Medvedev, whose tour of the region includes a visit to Cuba.
Although both Cuba and China are run by Communist parties, they have pursued very different economic models.
China has adopted market economics while Cuba still has a command system with most of the economy under state control.
When Mr Hu last visited Cuba in 2004 Fidel Castro was still in charge of the country.
Raul Castro has introduced some reforms since he officially took over.
The younger Castro saw China as a potential model for Cuba to follow, says BBC regional analyst Emilio San Pedro.
China, a modern-day economic powerhouse in a world of financial uncertainty, sees Cuba with its need for investment and political support as an important ally in its long-range plans to strengthen and expand its ties with the rest of Latin America, he adds.