The invention relates to a nested trichotomy-based robot execution end obstacle avoidance path planning method. The method aims to obtain a planned path with a minimum length for a robot execution endfrom a starting point to a target point on the premise that the robot execution end avoids an obstacle. The method includes the following steps that: various data are initialized; the obstacle is enveloped into a straight prism; a module for judging the intersection of the connection line of the starting point and the target point and the obstacle straight prism is called, if the connection lineof the starting point and the target point does not intersect with the straight prism, such kinds of condition is denoted as a condition A, the connection line of the starting point and the target point is considered as the planned path with the minimum length; and if the connection line of the starting point and the target point intersects with the straight prism, such kinds of condition is denoted as a condition B, a nested trichotomy module is called, and the planned path with the minimum length includes three segments, namely the first segment path of a straight-line distance between the starting point and a first intermediate point, a second segment path of a straight-line distance between the first intermediate point and a second intermediate point, and a third segment path of a straight-line distance between the second intermediate point and the target point; and the method terminates. The method has the advantages of simple concept, easiness in implementation and high robustness.