A new method for detection of moving trajectory of pixel-sized target from a time sequence in high noise environments is presented in this paper. Based on the continuity of the moving trajectory of target

the structure of a quasi-continuity filter（QCF） is built. And a forwardbackward filter algorithm is used to filter most of noise pixels out effectively. Then the properties of trajectory are embedded in an objective function and the trajectory detection problem becomes the problem of minimizing the given objective function. Furthermore

A* algorithm can be used to solve a shortest path problem on a weighted graph to get the target moving trajectory. Finally

experiments will show the advantage of this method for detection of arbitrary target trajectories in high noise environments without the major drawback of limirted detectability wirthin the predefined trajectory set or massive computation that most other algorithms suffer from.