Abstract: Vibration energy harvesting technology can convert the vibration energy of equipment working conditions into electrical energy, which provides a new idea for realizing self-powered wireless monitoring nodes in coal mines. In this paper, we design a linear-arch composed beam tri-stable piezoelectric energy harvester by introducing nonlinear magnetic force, and analyse the influence of the horizontal distance, vertical distance and excitation acceleration on dynamic characteristics. The nonlinear magnetic force model is established by the magnetic dipole method, the nonlinear restoring force of the linear-arch composed beam is measured experimentally, and the restoring force model is obtained by polynomial fitting. The dynamic model of the system is established based on Euler-Bernoulli beam theory and Lagrange’s equations. From the perspective of time domain, we analyse the influence of the horizontal distance, vertical distance of the magnets, and excitation acceleration on the dynamic characteristics of the system. A prototype of a linear-arch composed beam tri-stable piezoelectric energy harvester was fabricated, and an experimental platform was built for experimental research, by collecting the response speed data at the end of the composite beam after being excited, the speed-displacement data at the end of the composite beam was obtained, which verified the correctness of the theoretical simulation. The results show that the introduction of a nonlinear magnetic field can make the potential of the system have single potential well, double potential well or triple potential well. When we keep the excitation is constant, adjusting the horizontal and vertical spacing of the magnets can enable the system to achieve monostable, bi-stable or tri-stable motion, and the response displacement is relatively large during tri-stable motion. Increasing the excitation acceleration is beneficial for the system to across the barrier and achieve a large response. The research provides theoretical guidance for the design of linear-arch composed beam tri-stable piezoelectric energy harvester.