Abstract: It is revealed by the field test on the filter element for coalescence filtration under high pressure, its filtration efficiency on the particles with size less than 4 μm is reduced obviously for the packed density of the partial filter layer decreases with the continuous shock of the high-pressure air flow. In this paper, the filtration performance of polyester fiber(PET) and polypropylene fiber(PP) filter elements with the surface density of fiber layer in the range of 13-50 g/m2 was measured respectively using the gas-liquid filtration performance evaluation system. And the following results were obtained. With the increase of the surface density of filter fiber layer, the pressure drop of filter element increases and the mass concentration of the liquid droplets at the outlet decreases. The measurement is basically in agreement with the field test result of filter element. The steady-state pressure drop of PP filter element is much lower than that of PET filter element, and the performance of PP filter element varies greatly with the surface density of fiber layer. Then, the experimental results were compared with the theoretical values of filtration efficiency model corrected with packed density. And it is indicated that the error between the experimental result and the theoretical value of PET filter element is less than 1%. The research results are, to some extent, of practical engineering significance, and they provide reference for the optimization design of filter elements that are actually applied in the engineering.