Abstract: Due to the problems of randomness and low computational efficiency of the traditional sampling algorithm, a heuristic sampling algorithm, taking the kinematic constraints of the arms into consideration, was proposed. The automatic path planning using heuristic sampling algorithm was achieved by establishing the Lagrangian dynamic model of 2 degree of freedom(2 DOF) manipulator, and the joint angle and angular velocity which implemented the real-time detection of joint torque, was obtained by using the integrator in sampling angular acceleration. The trajectorys of angle and angular velocity of the two joints under different loads were simulated with MATLAB and compared with that of B-spline method. The result of the simulation verifies that the trajectory can be planned automatically under different loads by using heuristic sampling algorithm, which has advantages in timeliness and path planning.