In order to maximize the use of piezoelectric cantilever beam generator for collecting environmental vibration energy and ensure that the piezoelectric cantilever beam external load can work properly based on the principle of circuit load impedance matching, it is necessary to study the effect of the structure parameters of the piezoelectric cantilever beam on its optimal output power and the corresponding external load matching resistance. In this paper, the influences of the length, thickness, width and mass quality of the substrate and the piezoelectric ceramic piece on the optimal output power of the piezoelectric cantilever beam and the corresponding load matching resistance are studied by means of piezoelectric circuit analysis. The results show that the external load matching resistance of the piezoelectric cantilever beam can be increased significantly with the increase of the length of the substrate, the thickness of the piezoelectric ceramic piece and the quality of the mass within a certain range, and the external load matching resistance of piezoelectric cantilever beam can be reduced significantly with the increase of the thickness of the substrate, the length of the piezoelectric ceramic piece and the width of the piezoelectric ceramic piece. With the increase of the length of the substrate, the width and length of the piezoelectric ceramic piece, and the quality of the mass, the output power of the piezoelectric cantilever beam is improved significantly, the width of the substrate has no effect on the output power of the piezoelectric cantilever beam, with the thickness of the piezoelectric ceramic piece increasing, the optimum power of the piezoelectric cantilever beam increased first and then decreased, and there is a maximum optimal output power.