Abstract: Applying the method of spray drying and using powder collecting rate and PDI as index to study the influence of feed temperature,inlet air temperature,feed flow and atomization pressure on spray drying,the high quality of watermelon seeds protein powder were obtained. The optimal preparation technology was obtained by uniform experiment. The optimal preparation conditions were feed temperature 20 ℃,inlet air temperature 180 ℃,feed flow 300 m L/h,atomization pressure 140 k Pa. The result showed that the rate of powder collecting was 50.43%,protein dispersion coefficient(PDI) was 80.1%,and the state of protein was powder,milk white,no smell,no lumps and the functional properties of protain was good.