Aiming at low response performance of vibration energy harvester to low-frequency and low-amplitude excitation, the nonlinear magnetic attraction is added to energy harvesting structure to improve frequency band and energy conversion efficiency. Nonlinear magnetic models are studied, the distributed electromechanical coupled models of transverse and longitudinal vibrations are established by using the generalized Hamilton variation principle, and system dynamic equation is addressed dimensionless and solved numerically. The experimental platform of vibration energy harvester is built, the spectral characteristics and response output is obtained. Results show that, when magnet spacing is 15mm and excitation amplitude is 0.5m/s2, the energy conversion efficiency increases by about 6 times compared with that with no magnetic, and resonance frequency decreases from 18Hz to 9.5Hz, which solves problems of narrow band, high response frequency and the low output voltage of piezoelectric energy harvester.