The invention provides a milk vetch seed sowing device matched with a rice harvester. The device comprises a machine frame and a material storage barrel, wherein an electric butterfly valve is mountedat the lower end of the material storage barrel; a discharging pipe is mounted at the lower end of the electric butterfly valve; a perforated plate is mounted at the lower end of the discharging pipethrough screws; a motor is mounted on the lower end surface inside the machine frame; sowing wind wheels are mounted at the output end of the motor; a cover body is sleeved outside the sowing wind wheels; the discharging pipe extends into the cover body; and two ends of the cover body are hinged with baffles; the middle parts of the upper ends of the baffles are rotationally connected with roundrods; sleeve barrels sleeve the round rods; one end of each the sleeve barrel is rotationally connected to the upper end surface of the cover body through a rotary shaft; a plurality of threaded holesare equidistantly formed in the outer surfaces of the round rods; round holes are formed in the outer surfaces of one end, far away from the cover body, of the sleeve barrels; and connecting bolts are arranged in the round holes. Compared with the prior art, the device has the following advantages: convenient adjustment of sowing range, seed sowing quantity and sowing uniformity is realized.