China is Cuba's second-most important trade partner after Venezuela and one of its principal sources of credit.
A government statement said the meeting was "fruitful and touched on a number of themes".
Wu will travel to Colombia and Chile on official meetings after his Cuban visit.
The condition and exact ailment of the Fidel Castro, 80, remain state secrets, but he is largely believed to suffer from diverticular disease, which can cause inflammation and bleeding in the colon.
He has not been seen in public since before July 31, when he announced he had undergone surgery and was provisionally ceding his powers to his brother while he recovered.
Since then, he has been seen only in photographs and videos released by the government, initially looking thin and weak but more recently appearing stronger.
No new images of Fidel Castro, either on video or in photographs, were shown during Friday's brief television news report.
After meeting Fidel Castro for an hour and delivering a letter from Hu Jintao, the Chinese president, Wu met Raul Castro to discuss economic and other issues, Prensa Latina said.