To solve the problem of moving objects located difficultly under complex background, a tracking algorithm based
on AdaBoost is proposed. Firstly, an ensemble of weak classifiers is trained online to distinguish between the object and the background. Then, the ensemble of weak classifiers is combined into a strong classifier by using AdaBoost, and strong classifier is used to label pixels in the next frame, and a confidence map is given. Finally, the new position of the object is found by using mean shift algorithm. Experimental results show that this algorithm is robust and can track the object accurately under the conditions of illumination variation, shape change of object and partial occlusion.