More than 300 million Chinese are expected to tune in to the series about one of their favourite adopted sons, Rewi Alley.
The five-part series is a co-production between China's state broadcaster CCTV, Dunedin-based production company NHNZ and the Ministry of Culture and Heritage.
"Rewi Alley is hugely popular in China, and New Zealand continues to gain significant benefits from his status as a well known and highly respected figure," Mr Key said.
The five-part series, which will screen tomorrow to coincide with New Zealand's "national day" at the Shanghai Expo, examines the achievements of the New Zealander.
Mr Alley devoted six decades of his life to helping the Chinese people, and re-enforcing the "positive image of Rewi Alley" to a combined audience of 300 million people would help strengthen the relationship between the two countries, Mr Key said.
Mr Alley, who had worked in a variety of roles, won recognition in China by establishing the "gung-ho" industrial co-operatives, and for his education work and writings.
The launch topped a busy programme for Mr Key who arrived in China yesterday.
He also announced agreements and initiatives to strengthen co-operation between the two countries.
A film co-production agreement would allow film makers to access funding available for national movies and would also facilitate temporary immigration and equipment importation within the existing regulations.
Discussions have begun for a similar agreement over television co-production.
On Tuesday, cattle breeders Te Mania and food safety packaging firm FoodCap signed an agreement with Chinese investment company Kerchin, and New Zealand's ambassador, Carl Worker, and Chinese Vice-Minister of Science and Technology Cao Jianlin yesterday signed a strategic research alliance to link education, research and markets.
Mr Key said the co-operation between countries would ensure research results returned economic results.
"China is now one of New Zealand's top 10 partners for scientific collaboration and enhanced co-operation had the potential to deliver real benefits for both partners."
Mr Key said he had a very good meeting with China's Premier Wen Jiabao.
"I presented the ambitious goal of trying to double our two-way trade by 2015 and Premier Wen thought that was achievable and something they were prepared to support," he told journalists following the meeting in the Great Hall of the People.
Two-way trade between the two countries is worth $10 billion annually.
