Abstract: A self-moving robot and a method of automatically determining an accessible region are provided. The self-moving robot performs a setting process of 2D obstacles to generate a goal map based on an exploration map, performs a setting process of 3D obstacles on the goal map to update the accessible region of the goal map when a 3D obstacle is detected, performs an avoidance action, and, moves within the accessible region of the goal map. The disclosure prevents the self-moving robot from colliding with obstacles or being trapped.