In the light of the special requirement of inner surface observation of cannon barrel and considering the shortage of traditional image mosaic, a kind of panoramic image mosaic method is presented combining hardware and software, which is based on rotated scanning serial inner surface image. In this method, a reflector with 45° angle and synchronous ratation of a CCD camera driven by a step motor are used to get the equidistant serial inner surface images quickly, then the inner surface full image are coarse mosaic according to the step angle based on the serial images. During the mosaic the rotator step angle θ and the image pixel distance P calibrated first, then the sub-district to be matched are chosen according to calibrating, after that the precision matching on sub-pixel degree are implemented based on phase correlation, so mosaic of the serial images is realized in high precision. In order to obtain a smooth transition in full image seam Gaussian functions weighted amalgamation algorithm based on human visual system(HVS) character is used to blend images. Simulation and test shows that the algorithm can generate the seamless full image of the inner surface quickly and in high precision, the mosaic precision can reach sub-pixel and the time consumption is less than 500 ms,which can meet the real-time observation requirement, and suit to engineering application.