Digital holography can record and display three-dimensional information of objects, and is widely used in many fields. Due to the coherence of the light source, the digital hologram is destroyed by speckle noise, which seriously influences the quality of the reconstructed image. In order to remove speckle noise, in this paper, we combine random overlapping masks and 3D block matching filtering. This method uses only one hologram, which is simple and time-saving. The experimental results show that when the image noise is large, the proposed method can still achieve higher peak signalto-noise ratio (PSNR) and structural similarity (SSIM), especially the structural similarity, reaching 0.99, and meanwhile the relative deviation and visual effect both are excellent.