A four-wave-plate electrooptic polarization controller (PC) is constructed with their fast axes oriented alternately at 0°, 45°, 0°, 45° with respect to horizontal. The simulated annealing feedback controlling algorithm is applied to the controlling process to get the desired output polarization state. Simulating results show that this polarization controller is endless and the plate phase range can be limited within 0 to 2π. Using this controlling algorithm the controller can converge rapidly and the fluctuation of light intensity is less than 2%. To ensure the endless property of the controller a coercing reset method is introduced and here the reset process is stable. In searching the optimal value, the phase shift step of plates is variable but less than the maximum step of 3.36° while the step is fixed in 18° for the coercing reset.