Farmland sewage multi-stage filtration treatment device

The invention belongs to the technical field of sewage treatment, and particularly relates to a farmland sewage multistage filtration treatment device which comprises a first box body, a second box body and a third box body, the second box body is transversely arranged, the first box body is located on the left side of the second box body, and the right side of the bottom of the first box body is communicated with an opening in the left end of the second box body; the left side of the top of the third box communicates with the right end opening of the second box. The filter assembly is arranged in the second box body; a conical filter cartridge is also arranged in the third box body; the filtering assembly comprises a first filtering module, a second filtering module and a third filtering module, when the filtering assembly is blocked, a floating block floats upwards along with continuous increase of the water level in the first box body, and then the filtering assembly is pulled to swing rightwards, so that