The improvement of the output power of the existing nonlinear piezoelectric energy harvesters is mainly realized by changing the structure or introducing into the nonlinear elements. However, these methods have limited ability to improve the output power of the devices and broaden the harvesting bandwidth. In this paper, a doublecantilever piezomagnetoelastic structure is designed to optimize the harvester. In addition, by setting permanent magnets, the output voltage can be further improved, and the bandwidth can be broadened. The double cantilever structure is equivalent to a cantilever with complex boundary conditions. The working state equations of the piezomagnatoelastic energy harvester are deduced and the relationship between the output voltage and the space of the permanent magnet is obtained and verified by experimental. The experiment results show that the maximum output power is obtained when the distance between permanent magnets is 5 mm. Under the optimal permanent magnet distance and load resistance, the output power of the double cantilever piezomagnetoelastic energy harvester is 1.5 times as much as that of the conventional cantilever energy harvester and resonance frequency decreases about 7 Hz.