The utility model relates to an inlet filter of an air compressor. An angle steel frame is arranged at the left end of a filter case, a steel plate screen is mounted on the frame, a filter gauze is mounted at the front end of the steel plate screen in a distributed manner, a packing rack is fixedly mounted in the case, filter packing is filled on the packing rack, and a rear baffle plate is mounted at the rear end of the packing rack. The inlet filter of an air compressor is simple in structure and reasonable in design, the service life of the inlet filter is prolonged, and the inlet filter provides a better safety guarantee for a fan in operation, reduces contact with rain and snow so as to prolong the service life, and improves operating efficiency since the filter packing can be replaced without suspending the online filter.