Considering the piezoelectric actuators have characteristics of wide temperature resistance range， no electromagnetic interference， and self-locking when powered off， a novel inchworm piezoelectric linear actuator， which meets the demand of new actuators for small grasping operating mechanisms in the aerospace environment， is proposed imitating the walking mode of the insect inchworm. A flexible hinge-type displacement amplifying mechanism is utilized to amplify the output displacement of the Pb-Zr-Ti （PZT） stack， so as to increase the movement step length of the linear actuator and the clamping deformation of the guide rail. The multiple PZT stacks are divided into three groups， which are respectively used as two clamping units and one propulsion unit of the actuator to obtain a larger driving force and further increase the movement step. Through the finite element analysis method， the prediction method of the electromechanical coupling behavior of the PZT stack is studied， and the feasibility of the method is verified by experiments. The flexible hinge displacement amplification mechanism is simplified， and the numerical analysis method of magnification is proposed. On this basis， an experimental study is carried out based on the designed linear actuator. The test results show the magnification of the output displacement of the PZT stack by the displacement amplifying mechanism is 7.3， which is between the theoretical value and the simulation one. When the excitation voltage frequency is 5 Hz， the maximum no-load moving speed of the actuator is 413 μm/s； the maximum driving force is 16 N， corresponding to a driving speed of 19 μm/s. The above research results can provide technical support for the intelligent drive of small grasping operating mechanisms.