Abstract: In measurement of environmental particles, PM_2.5 separators are a core component for screening of particle sizes and accurate collection of particles. The test and evaluation of separation performance is of great significance in research on particle meters. The separation performance test device is used to evaluate the separator’s performance, which can give the performance curve and judge whether the separator meets the designed requirements. So the test device affects the accuracy of the separation performance. Through the evaluation of the key parameters, feasibility and comprehensive performance of the test device, it will provide a theoretical and experimental basis for the accuracy and reliability of the device in application.