Objective: In order to effectively solve the problems of low efficiency, quality fluctuation and increasing labor cost of artificial sorting. Methods: A mechanical system based on differential separation principle was designed to complete the classification and separation device of Pleurotus eryngii, and the differential separation principle was introduced and modeled. Results: The test prototype was built and the principle verification test was completed. The success rate of separation of special mushroom was 99.5%, and that of other varieties was 100%. Conclusion: The test device can achieve good differential separation effect.