Xiguang, a 4-year-old male Asian elephant, became addicted after he was captured by smugglers along the Chinese-Myanmar border in March 2005. The traders fed the elephant bananas laced with heroin as bait and to pacify the creature, the official Xinhua News Agency said.
When Xiguang was found two months later along with six other captured elephants in China's southwest, he was suffering from withdrawal and was sent to a protection center in China's tropical Hainan island.
Xiguang received daily methadone injections in doses five times larger than those given to a human and has now fully recovered, Xinhua said.
He is expected to return to the Yunnan Wild Animal Park in the capital of Yunnan province, Kunming, on Saturday.
The Asian elephant is threatened with extinction, according to the World Wildlife Fund conservation group, with only 25,600 to 32,750 left in the wild of Asia's tropical forests - fewer than a tenth of the number of wild African elephants.