Abstract: According to agronomic requirements of seed coating，a new seed coating device was designed.This device consisted of seeds quantitative supplying，liquids quantitative supplying，seed and liquid mixing，seed and liquid conveying，mixing chamber rotary cleaning and bucket elevator etc.This coating device could finish many operation links such as supplying seed，supplying liquid，mixture and transportation of seed and liquid at one time.Design of impeller quantitative supply device avoided question that effecting displacement accuracy of large seeds because of smaller depth of outer groove wheel notch.A timely and accurate supply of seeds was ensured.Design of staggered three section spiral auger transmission mechanism that not only could ensure delivery capacity，but also could better protect seed.Design of ladder shaped taper swinging disc that using centrifugal movement and horizontal projectile motion，which could achieve seed evenly distributed in space，so that seed and liquid mixture were more uniformly.Moreover，bucket elevator for the seeds to match coating device was designed.