The noise of the high-speed X-ray line array detector was analyzed. The detector noise was divided into three types, the background noise, random noise and isolated noise. By experiment, the noise change with the detector scanning speed increase was studied, and the impact of noise on the detection result of the detector was analyzed. A filtering method for high-speed X-ray line array detector was proposed. Difference method filters out the background noise and Kalman filter filters out random noise. According to the noise characteristics, the improved median filter filters out noise isolation. Experimental results show that the method not only can effectively filter out all kinds of noise of the detector, but also keep the details of the detector detects image.