To reveal the influence of the parameters of the bi-stable piezoelectric energy harvester（BPEH）system based on lineararch composed beam on its dynamic response characteristics，the nonlinear magnetic model of the BPEH is derived with the magnetizing current method and the distributed parameter model of the system is acquired by the generalized Hamilton variational principle. Then，the harmonic balance method is used to analyze the response characteristics of the energy harvester system. The influence of different magnet distance，excitation amplitude，load impedance and other parameters on the system's amplitude-frequency response and output power is discussed and verified by experiments. The research results show that the amplitude-frequency response of the BPEH system has jumping and multiple solutions，and the range of the unstable region can be adjusted by changing the magnet distance and the excitation amplitude. In addition，the external excitation frequency is a key factor affecting the optimal impedance of the system，and the magnet distance and excitation amplitude have no significant effect on it. When the system magnet distance d is 16 mm，the excitation frequency f is 16.2 Hz，the optimal resistance R is 5.6 MΩ，and the excitation amplitude A is 1.3g，the maximum output power of the system is about 43.4 μW. The research results provide a theoretical basis for the optimal design and engineering application of the BPEH.