Some analyses and experiments of detecting moving track of video objects based on successive frame subtraction are proposed.A method of synthesizing the object moving track by part moving tracks is suggested.First,the difference image between current frame and previous frame is processed in contrast enhancement,and is devided into blocks;second,weight of every block image is calculated and forced to zero if the weight less than a threshold,so these blocks of moving objects are reamained;third,all adjacent blocks are grouped;last,the weight position of every groups are calculated,that is the position of moving objects.The researching results have proved the speediness and validity of the detecting method.