Improving the filtration performance of prefilters to protect high efficiency filter media is of great significance for air conditioning systems. Based on this, a schorl/polyester composite (SPET) filter was produced by embedding schorl powder into a polyester (PET) filter surface via a thermoplastic polyurethane (TPU) membrane. Its filtration performance parameters, including pressure drop, filtration efficiency, and quality factor (Q), were studied experimentally and compared with those of PET. The filtration efficiencies of the SPET filter for dust particles with diameters between 0.3 and 10 mu m were improved, with a more significant enhancement effect for smaller dust particles. Additionally, the quality factor was improved by the addition of schorl powder to make SPET. The enhancement mechanism of SPET has been studied. The electret filters model made good predictions of the filtration efficiencies of SPET by ignoring the piezoelectricity of schorl. This study indicates that the spontaneous polarization of schorl is the main reason for filtration efficiency enhancement. (C) 2018 Published by Elsevier B.V.