The utility model relates to a horizontal backwashing sand filter for irrigation, which comprises a tank body, a water inlet pipe, a water outlet pipe, a backwashing dirt discharge pipe, a baffle plate, and a sand charging hole, wherein a perforated filer element plate is arranged in the tank body, and a filtering device is arranged on the filer element plate; an enclosed cavity body is formed from the filer element plate and the lower part of the inner wall of the tank body, and the enclosed cavity body is communicated with the water outlet pipe. The utility model is mainly used for agricultural irrigation.