Self-propelled robot and automatic determining method of an accessible region thereof

A self-propelled robot and an automatic determining method of an accessible region are provided. The self-propelled robot executes a setting process of 2D obstacles to generates a goal map based on a search map, executes a setting process of 3D obstacles on the goal map for updating the accessible region of the goal map when any 3D obstacle is detected, executes an avoidance action, and moves in the accessible region of the goal map. The disclosure can prevent the self-propelled robot from colliding with the obstacles or being trapped.