On the basis of the mechanism of Smear effect and the image characteristics of a frame transfer CCD camera, a Smear removal algorithm which is based on the high precision background estimation is proposed. It can be applied to not only a single picture, but also sequences for imaging systems. This method firstly uses a statistic method to analyze the gray distribution of an original image to get the specific location of Smear effect automatically, then it takes Alpha-trimmed Mean Filter (ATMF) to estimate the intensity of the Smear effect exactly. Finally the difference way is used to eliminate the Smear effect. Experimental results show that this method can effectively eliminate the single or multi-Smear effects,and can ultimately improve the image quality.The proposed method meets the requirements of astronomic observing cameras for Smear removal.