The present invention provides a clamping device for a foup box, a foup device and a fixing method thereof. The clamping device for the foup box comprises a clamping mounting plate, a guide rail sliding block mechanism, a sliding block connection plate, a clamping support plate, a clamper, a cylinder connection plate, a cylinder and cylinder support plates. According to the invention, a foup box silicon wafer can be subjected to side operation to eliminate the restriction on the operation position of the foup box, the reliability is high, the structure is reasonable, and the regulation is convenient.