System and method for graphically allocating robot's working space are provided. The system includes an image extractor, a task-allocating server and a robot. A graphic user interface (GUI) of the task-allocating server includes a robot's working scene area, a space attribute allocating area and a robot's task area. Thus, a user assigns one certain space area in the robot's working scene area with a “wall” attribute, or another space area with a “charging station” attribute. Meanwhile, by using the GUI, the user directly assigns the robot to execute a specific task at a certain area. Hence, the user or remote controller facilitates the robot to provide safer and more effective service through his/her environment recognition.