Abstract: Since the portable X-ray machine has been widely used, the de-noising of its images is important. This paper discusses the noise sources and characteristics of the portable X-ray system, proposes a new compound algorithm of image de-noising to overcome the drawbacks of conventional algorithms. This compound algorithm can effectively filter out Gauss noise and impulse noise, while retaining image details. The simulation result verifies the feasibility and efficiency of the proposed method.