Abstract: Objective To analyzed Morris water maze video based on the usage of ImageJ. Methods USB camera and common PC (Intel Pentium 4 CPU 1,70GHz) were used, and it's not necessary to mark the animals. After the procedures of setting scale, removing background and binaryzation with ImageJ, we used MultiTracker，an ImageJ plugin ,which can track the movement of multiple objects，to analyze the results. Result Swimming paths of rats and paths can be successfully analyzed. Conclusion This method based on a free software and low hardware requirements, can get all necessary date of Morris water maze.

Key words: ImageJ, Morris water maze, ethology, video, trajectory analysis