In this work,the waveguide effect inside the high high-aspect-ratio metal structure of hard X-ray photon sieves is studied based on fast fourier transform beam propagation method （FFT-BPM）. After the physical boundary condition immediately downstream of hard X-ray photon sieves is determined by FFT-BPM, the angular spectrum method is used to calculate the point spread function，and the absorber thickness impact on the focusing performance is analyzed. The results show that the waveguide effect can suppress the emergence of the high order diffraction of hard X-ray photon sieves to some extent,thus improve its focusing performance.Under the same feature size conditions, the spatial resolution of hard X-ray photon sieves is better than that of Fresnel zone plates,with the drawback of lower diffraction efficiency.With the absorber thickness increasing, both the focusing performance and diffraction efficiency of photon sieves will improve, but the difficulty of the corresponding nanofabrication process will also increase.