Abstract: A linear actuator includes two spaced seats connecting by a center piezoelectric member. The seats are mounted in a rail frame. Each seat has a piezoelectric member and an elastic zone for engaging or disengaging with the rail frame. Through energizing and disenergizing the center piezoelectric member alternately, the center piezoelectric member may be extended or contracted alternately, and thus moves the seats, consequently the actuator, longitudinally along the rail frame. A linear and accurate movement of the actuator thus may be achieved at micro meter level.