Several moving objects detection methods were compared and an improved method on the basis of consecutive frames difference was proposed. Color images captured with camera were transformed into gray ones and the gray ones were processed with median filter. The adjacent frames of any three consecutive ones were handled with differential operation to obtain two difference images and threshold value was set to transform difference images into binary ones. The binary images were dealt with by using opening operation. The location of moving aircraft was determined by performing two difference images with AND operation. The simulation results show that the improved method can effectively detect and locate the moving aircraft in intelligent surveillance system.