Embodiments of the present application disclose a passive intermodulation suppression method and a passive intermodulation suppression system. The method in the embodiments of the present application includes: obtaining, by using a target uplink controllable gain module, a first power Pt of an uplink signal sent by an antenna; obtaining a second power Pb of a signal that is output from an output port of a base station; configuring a target attenuation of the base station; and adjusting the initial gain value based on the target attenuation to keep a gain of the base station constant. According to the method described in the embodiments, the base station can maintain the target attenuation constant in a process of adjusting a gain of the target uplink controllable gain module, thereby reducing a PIM requirement of a passive intermodulation suppression system.