Customs authority in Hangzhou, capital of east China's Zhejiang Province, said 469 tons of solid waste will be returned.
Inspectors found the shipment, from the United States, consisting of scrap paper mixed with waste metal parts and used drinking bottles.
According to Chinese regulations, the shipment that contains solid waste should be banned from import.
The customs authority has asked companies to return the waste as early as possible.
China has banned imports of 24 types of solid waste since late 2017 in a move to reduce environmental pollution.