Based on the speckle suppression theory of the superimposed statistically independent speckle image, a mask with N apertures is designed. It is placed in the pupil plane of the imaging lens. Required conditions of producing the statistically independent speckle images are studied theoretically. In the simplified optical system, diffuser and the detection plane of the CCD are placed on the conjugate imaging planes of the lens, respectively. The effects of the center spacing between the adjacent apertures and the single aperture diameter on the formation of statistically independent speckle image are experimentally analyzed. Diameter of the single aperture has an effect on the speckle particle size. Without considering the impact of the experimental apparatus on the measured accuracy, the experimental results agree with the theoretical analysis.