The present invention relates to a self-alarm multi-stage complex screen filter for micro-irrigation and the assembly method thereof. The filter comprises a housing, an alarm, a multi-stage screen filtering element, and a segmented brush. The housing comprises a left housing, a middle housing, and a right housing. The multi-stage screen filtering element comprises a plurality of screen filter cylinders. The segmented brush comprises a plurality of bristle frames, a plurality of connecting rods, a connector and a power device. The middle housing is provided with a water inlet. The left housing is provided with a discharge pipe. The installation, disassembly, repair, maintenance of the filter of the present invention can be done more conveniently.