Targeting the requirement of implantable micropump in the field of biomedicine, in order to increase the output flow rate of micropump under low voltage and miniaturization conditions, a piezoelectric valveless implantable micropump with double-layer pump chamber was designed in this paper. Based on the piezoelectric coupling simulation of the piezoelectric vibrator and the electric-solid-fluid three-phase coupling simulation of the proposed micropump, the validity of the design of the double-layer chamber micropump was verified, and the structural and driving parameters were optimized. The experiments were carried out to verify the feasibility of the results of the coupled simulation and the flow range of the proposed micropump was tested. The results show that the optimal design parameters of the micropump are as follows: the diffusion angle is 30°, the neck width is 300 μm and the height of the upper pump chamber is 100 μm. The net flow of micropump increases with the increase of voltage, and it is suitable for low-frequency drive. The experiments results show that the output flow rate of the double-layer pump chamber piezoelectric valveless micropump is 5.38 times higher than that of the conventional piezoelectric valveless micropump.