Addressing Vietnam's National Assembly on the second day of a three-day state visit, the Chinese president appealed to shared ideology, saying China and Vietnam could work together in the name of socialism, despite their long rivalry.
Speaking through a Vietnamese interpreter, Mr. Hu said the former enemies had much in common.
Mr. Hu said China and Vietnam have mountain ranges and rivers adjoining each other and share a flow of culture and ideology, so their interests are closely connected.
Vietnam and China fought a border war in 1979, but the two communist countries have more recently become united by bilateral trade, which totaled more than $7 billion last year.
But most of that trade is one way. China exported more than $4 billion in cheap products to Vietnam last year, but Vietnam exports little more than half that amount to its giant northern neighbor.
In his speech Tuesday, Mr. Hu did not mention the trade imbalance, but urged Vietnamese to emulate the Chinese experience in export-driven market reforms. He touted China's boom in foreign direct investment, up nearly 10 percent this year, and also his country's exports, up 24 percent so far this year.
The Chinese president told his Vietnamese hosts that his country's economic growth was the result of China's special brand of market-socialism, a philosophy Mr. Hu urged his fellow communists to follow.
Vietnam has enjoyed some investment spillover from China. Two years ago, most of Vietnam's foreign investment went to Ho Chi Minh City in the south. But recently the northern capital of Hanoi has seen the biggest surge, accounting for nearly half of the $3 billion in foreign investment this year.
Vietnam's Chamber of Commerce says much of the northern investment boom comes from countries that already invest in China, but want to spread their risks. Also wages in northern Vietnam are lower than in parts of China, and some foreign companies are building factories north of Hanoi in hopes of exporting to China.
But Vietnam, like other countries in the region, has reason to be worried about being overwhelmed by China's explosive economic growth.
This week's visit by Mr. Hu is a milestone in fraternal communist relations, but Hanoi still has reason to view its communist brother to the north with a wary eye.