Abstract: A new bionic action principle of linear actuator is presented.The two prototypes of linear actua-tor on this action principle and its controller are designed.Experiment results show that the actuator func-tions and performs with ultrahigh accuracy,changeable steplength,large drive force,long stroke and bestoutput,characteristic due to built-in sensor,although it is simple in structure,small in volume. These actua-tors are applied to all ultrahigh accuracy direct drive.