To improve the environmental adaptability of a piezoelectric vibration energy harvester， a magnetically-coupled tunable piezoelectric vibration energy harvester （PVEH） is proposed. The coupling action between the active magnet on the actuator and the passive magnet on the combined transducer and transversal spring was used to realize the unidirectional limiting excitation of the piezoelectric vibrator. Through modeling and simulation analyses of the energy harvester and magnetic pair， influences of the structural parameters of the energy harvester on the corresponding output performance could be determined. On this basis， the energy harvester prototype was developed by selecting a better magnet diameter via experimental research. The influence laws of the energy harvester's longitudinal mass m₁， transversal mass m₂， transversal magnet spacing L_x， longitudinal magnet spacing L_y， vertical magnet spacing L_z， and load resistance on the output performance were also obtained. The results show that two order resonant frequencies f₁ and f₂ cause the output voltage to peak to U_n1 and U_n2， respectively. Moreover， adjusting m₁， m₂， L_x， L_y， and L_z will affect f₁， f₂， U_n1， and U_n2. Therefore， the effective frequency band and output voltage of the energy harvester can be increased when appropriate structural parameters are selected for the energy harvester. When other conditions are given， there is an optimal load resistance of 2 200 kΩ that increases the output power to 0.122 mW. Therefore， the effective frequency band and output voltage of the energy harvester can be improved by selecting suitable structural parameters and distance between magnets. The results provide good reference value for enhancing the reliability and frequency adaptability of the PVEH.