A laser beam alignment system based on parameters self-adaptive proportion,integral and differential(PID) control algorithm was presented.It thoroughly solves the shortages of low accuracy,low frequency-response of traditional PID control method.In 50 minutes,the angle excursion of emergent beam in x direction (horizon direction) is 22 nm/150 nm,in y directioin (vertical direction) is 15 nm/150 mm the displacement excursion of emergent beam in x direction is 26 nm/150 mm,in y direction is 28 nm/150 mm.Experiments shows that accuracy and robustness of the laser alignment system have been greatly improved by employing parameters self-adaptive PID control algorithm.