Taking the multi-directional piezoelectric vibration energy harvester as the object, a simplified electromechanical coupling dynamic model of the system is established, and the finite element model of the energy harvesting device is constructed by COMSOL software. The vibration modes of the system are analyzed, and the effects of different structural parameters of the system on its voltage frequency domain response and load power impedance matching are discussed. The effects of different magnetic spacing on the electrical response are investigated by introducing nonlinear magnetic force. The results show that the peak values of load voltage and load power of the energy harvester can reach 37 V and 6.9 mW respectively under the acceleration load of 1g(g=9.8 m/s2) in y direction. Reducing the thickness of piezoelectric ceramics, spring substrate and increasing the weight of additional mass block is more advantageous for energy harvesting, and the energy harvester has an autonomous tuning function under the action of magnetic force, which enhances the environmental adaptability.