Abstract: The efficiency measurement is very important in the development of moisture separator.In this paper one moisture separator efficiency measurement system has been set up on the basis of the re-searches on both the foreign MSA type moisture separator and the innovative domestic one.The weight fil-tration efficiency is obtained by means of direct water weight measurement.The count filtration efficiency is measured by two Cassella Impactors which are used to sample the droplets in the downstream and upstream of the separator and one microscope which is used to observe the number of the droplets.The experiment result shows this efficiency measurement system is accurate and dependable.