Abstract: Aiming at problems of low film forming，uneven coating and high rate of seed damage，a new type of seed coating machine based on air suspension was designed according to national requirements for seed coating operation.Through the introduction and redistribution of updraft and tangential airflow，seeds were kept in the state of floating and rotating，resistance of movement and seed wear were reduced.Quantitative dosing of metering pump and tangential spraying of nozzle ensured a stable seed ratio.The coating machine can complete functions of coating，drying and conveying at one time，so as to ensure high quality of seed coating and uniform film coverage.