Abstract: Lidar range image is particular information of lidar system that other imaging systems (such as IR imaging system and optical imaging system) can not provide. It is the foundation for precision target identification and attacking. How to denoise directly determines the accuracy of target recognition. According to the characteristics of the radar range image, a method was presented for streak tube imaging lidar based on contrast-modulation method. The noise contrast information of range image was extracted to modulate original image, so as to get noise image, and finally range image without processing was used to minus the noise image to get the image which was denoised. The research result shows that the effect of this denoising method is obvious and the edge information of range image also keeps intact. After denoising, the signal noise ratio (SNR) of the range image is significantly improved. The attributes of range image does not change. This is the advantage the other methods for range image denoising methods does not have.