Sudan Tribune said three people have been detained in the incident, and the workers were handed over to the United Nations-African Union mission in Darfur.
Mohamed Suleiman Rabih, mayor of al-Kouma, said the freed Chinese workers were in good health and they will soon go home.
He didn't say whether the kidnappers voluntarily released them or whether the release was part of a security operation, the Sudan Tribune reported.
The Tribune said the workers were part of a group of 15 hostages taken by gunmen near el-Fasher, the capital of North Darfur.
Although the Chinese have been released, the Sudanese abducted with them are still in captivity.
Rabih called on the kidnappers to release them.