Abstract: According to locally autonomous and remote control modes for a power transmission line inspection robot, an FSM (finite state machine) based motion planning method for obstacle navigation is presented. The obstacle navigation processes of the inspection robot are divided into several key discrete states, and FSM models for motion planning are established. A fuzzy-based production system is offered for deducing obstacle navigation modes and producing the motion sequences. Simulation and field experiments prove that the motion planning method for obstacle navigation is correct and valid, and can be applied to the motion control of power transmission line inspection robot.