In order to solve the problem of mechanical harvest of corn stubble, a roots-soil separating device of corn stubble was developed. It consisted of a double roller compacting mechanism and a dual flyweights-hit mechanism with flexible connection. The co-action of two mechanisms on corn roots-soil complex were compaction, rub, hit, impact and other ways to achieve the function of roots-soil separation. When the soil texture was medium loam and the soil moisture was 15%~20%, the test results showed that the average roots-soil separating rate was 98.12%, the roots-soil separating loss rate was 0.92% and the average efficiency reached 2.43 t/h. The device could realize the effective separation of stubble and soil. 