Since the beginning of the new century, the research on the field observation and test equipment has been developed, and many important results have been achieved. To overcome the shortcomings and deficiencies of the current test equipment, improve the level of soil erosion theory, scientifically prevent and control soil erosion, developing more advanced and practical soil erosion test equipment has a great significance. For the problems of measuring accuracy of automatic sand sampler and sand collection efficiency affected by strong wind interference, a shunthedging and multistage expansion combined reducing velocity method was proposed, a shunthedging and multistage expansion combined automatic sand sampler was designed, design principle of sand separator and data wireless acquisition system were expounded, and a test and analysis on reducing velocity and separation performance of sand separator, anti strong wind interference performance and collection efficiency of sand sampler were carried out. The results showed that shunthedging and multistage expansion combined automatic sand sampler had anti strong wind interference performance and it could collect data in realtime, continuously and in a long distance wireless. The starting wind speed of free rotation was 4.23m/s, equal dynamic property was 92.94%, average sand collection efficiency was 90.42%, when wind speed was less than 18m/s, as long as soil samples which particle was greater than 55.36μm entered sand sampler, can be fully collected, power supply battery life of data wireless acquisition system was up to 31h. The signal transmission distance was 208.51m without obstacles, which can well meet the automatic observation need for soil erosion mass.