Abstract: A novel precision piezoelectric step motor is proposed and its combination of electrorheological （ER） technology as an alternatives to mechanical valves device,thus achieving high precision and high-speed performance. The step motor is driven by the piezoelectric pump. The principle is the volume change of the chamber caused by thin-walled butterfly stretch and deformation of the hinge structure and this drives the precision hydraulic cylinder to complete a step. It adopts the principle of bionics and works with a new method of piezoelectric stack pump and a distortion structure of thin flexible hinge. It solved problems of the past piezoelectric precision stepper motor that the anchoring/loosen isn’t enough,low stepper-frequency and velocity,small travel,low resolution and the driving force of instability. The experiment shows that the novel linear piezoelectric step motor worked with high frequency （100 Hz）,high speed （502 μm/s）,large travel distance （10 mm）,high resolution （0.05 μm） and high load （ ＞100 N）. This kind of new piezoelectric step motor will be applied for large travel distance and high resolution driving device,optics engineering,precision positioning and some micro-manipulation field.