This study was aimed at optimizing the configuration of a vortex finder to improve the separation efficiency and reduce the pressure drop of cyclone separators. Six types of cone-shaped vortex finders were designed and tested for their performance on gas-solid separation at different flow rates and particle concentrations. The experimental results demonstrated that the reflux cone and gaps (straight and spiral) in a vortex finder could improve separation performance of the cyclone separator through reducing the pressure drop and increasing the overall separation efficiency and grade efficiency. The new cyclone separator with the vortex finder (Type D) that had both reflux cone and spiral gap (15 degrees dextrorotation) configurations had the best separation performance, which reduced the pressure drop by 73% and increased overall separation efficiency by 9% as compared to the cyclone separator with the basic vortex finder (Type A). This new cyclone separator removed 99% particles with a diameter bigger than 10 mu m. Our study indicated that the modified vortex finders (especially with both reflux cone and spiral gap configurations) have great potential for their application in gas-solid separation for natural gas cleaning. (C) 2013 Elsevier B.V. All rights reserved.