Please refer to FIG. 5. FIG. 5 is a flow chart of a method of determining zone usage in image according to an embodiment of the present disclosure. The method of determining zone usage in image disclosed in FIG. 5 is preferably used to determine whether the behavior of an object meets an event rule. Steps S01 to S07 disclosed in FIG. 5 are the same as steps S01 to S07 disclosed in FIG. 2, which will not be further described herein. Please refer to FIG. 5, wherein, after obtaining the detection zone (step S05) by performing the clustering procedure, not only step S07 can be performed to display the detection zone and another image by the display device, with said another image different from the plurality of images and associated with the image acquiring scene, step S08 can be performed to perform an event detection procedure to determine whether a behavior of a detected object meets an event rule. However, steps S07 and S08 described above can also be performed together. The event rule is one of the following, for example, a flow of objects in the detection zone, whether one of the objects exists in the detection zone (detection of an area that is forbidden for any entry), whether the time of one of the objects stays in the detection zone reaches a default time (parking detection), whether one of the objects in the detection zone moves in a default direction (detection of vehicle moving in the wrong direction), and whether a speed of one of the objects in the detection zone falls in a default speed interval (detection of driving over speed limit or below a minimum speed), the present disclosure is not limited thereto.