The falling particle solar receiver (FPSR) is a gas-solid two-phase flow receiver, which can realize the solar energy to thermal energy and also realize the thermal storage. Due to the particles escaped easily from the receiver and the radiant heat loss was increased greatly by setting semi-transparent in the aperture, which is to prevent the escape of particles. Thus, the structure of the FPSR should be carefully designed to improve the solar-thermal conversion efficiency. In this contribution, we studied the effects of the arrangement of the particle curtain, particle diameter and wind speed on the thermal efficiency of the receiver The result showed that the arrangement of particle curtain had a significant effect on thermal efficiency, and for different particle diameters, there was an optimal arrangement of the particle curtain so that the average temperature of the particles reaching the bottom of the receiver can reach 962.14K. However, the highest temperature that can be reached during the particle falling process was 1056.52 K, indicating that there was still a significant heat loss. On the other hand, at a certain wind speed, a natural air window would be formed at the aperture to prevent the outside cold air from disturbing the particle curtain. This contribution can provide a guidance for FPSR design to improve heat absorption performance.