The piezoelectric stackbased electrohydrostatic actuator incorporates a piezoelectric material and hydraulic systems through the rectification of the reed valve, make full use of the large displacement of the hydraulic system and high frequency operation of the smart materials, and avoid the defects of the complex pipelines of conventional hydraulic systems and the micro displacement of piezoelectric material. In this paper, a piezoelectric stackbased electrohydrostatic actuator was designed, a prototype was manufactured. The working principle and output flow formation mechanism was introduced. And experiments were carried out under different conditions to explore the factors affecting output flow and analyze specific impacts. The experiments shows that the maximum noload output flow of the prototype is close to 1.6 L/min at the peak frequency of 275 Hz, and the load capacity is apparently far more than 20 kg.