The express delivery service provider based in the United States is suspected of illegally transporting such knives to Hong Kong, the report said.
The knives were seized by Chinese authorities, and the case is still under investigation, it said. The report did not disclose where the knives were from.
It is not the first time that FedEx, which began operating in China more than three decades ago, has been accused of illegal actions.
In August, police in Fuzhou, capital of Fujian province, said they had seized a handgun in a FedEx parcel sent by a US client to a local company in Fujian.
In June, FedEx was investigated after Chinese telecom giant Huawei said FedEx had diverted two parcels sent from Japan and addressed to Huawei in China to the US.