The power source of windscreen wiper is motor, which is the core of the entire wiper system and is very high quality requirements. The wiper motor installed on the front windshield and worm gears are generally made of one mechanical part. The four-bar linkage of windshield wiper of automobile is driven by motor through worm gears. The method of simulated annealing is a technique that has attracted significant attention as suitable for optimization problems of large scale, especially ones where a desired global extremum is hidden among many, poorer, local extrema. The simulated annealing algorithm with penalty strategy is adopted to solve the optimal model of windscreen wiper mechanism, thus motion accuracy of wiper mechanism is greatly increased, and the searching number is greatly decreased.