In order to get the video image with large visual field in range instrumentation,a system of auto-stitching multi-lens image with large visual field is established and its applied algorithms,such as image matching,marking lapped area,seamless stitching and so on,are investigated.The theories of wavelet transformation and wavelet-packet are presented.An image-matching algorithm based on wavelet-transformation by matching wavelet parameters of image is analyzed.Then,the comparing and rotating algorithm to mark the lapped area is analyzed,in which the only lapped area is marked after sub-lapped areas are matched and rotated.Finally,the image seamless stitching algorithm based on wavelet-packet transformation is analyzed.After image wavelet-packet transformation,the wavelet parameters are merged by frequency and then the image is reconstructed using the result.Experimental results indicate that the system gets an image with 3.3°×1.76° large visual field by stitching four images with 1.1°×0.88° visual field,the stitched image is smooth and seamless ,the speed of the system can reach up to 10 frames/s.These results show that proposed stitching method can satisfy the requirements for range instrumentation in getting image with large visual field.