Imaging based on speckle autocorrelation is a research hotspot in the field of scattering imaging, but the statistical noise in the imaging process will affect the imaging results. In this paper, by utilizing the response of point spread function (PSF) to wavelength, we propose a method to improve the imaging quality of binary target. Since the PSF is sensitive to the wavelength, and the PSF corresponding to different wavelengths is different or even completely uncorrelated with each other. The autocorrelation superposition of different speckle patterns with uncorrelated PSFs can effectively suppress the statistical noise in the autocorrelation, and thus improve the quality of reconstructions. Simulation and experimental results show that, at the same detection distance and sampling area, compared to the single wavelength sampling failed in reconstruction, the proposed method can reconstruct the target completely and accurately.