"We are all sad about Xiang Xiang, but it doesn't mean the project has failed," said Zhang Hemin, head of the China Giant Panda Protection and Research Centre in Wolong.
"The lessons we have learnt from what happened to Xiang Xiang will help us adapt and improve the project."
A medical examination showed the 176-pound panda died of serious injuries, suffering rib fractures and internal damage.
Panda experts have speculated that Xiang Xiang might have fallen after getting into a fight with the original 'residents' for food or territory, Xinhua said, quoting Li Desheng, deputy director of the Wolong centre.
The animal's release came after nearly three years of training at the Wolong research centre to toughen him up for the wild.
Monitoring was to have continued until 2008 when the tracking device would drop off automatically after its battery ran out.
The giant panda is one of the world's most endangered species and is found only in China.
There are only thought to be about 1,600 wild pandas in the mountain forests of southwestern and central China, with more than 180 living in captivity.