The invention discloses a multi-mode piezoelectric power generator for power supply of an internet of thing node of a pneumatic system and aims to solve the limitation of relatively narrow energy collection bandwidth and low energy capturing efficiency of an existing linear pneumatic piezoelectric power generator. The multi-mode piezoelectric power generator comprises a rectangular container cavity, a vortex street driving device and a multi-mode piezoelectric power generation assembly, wherein the vortex street driving device and the multi-mode piezoelectric power generation assembly are arranged in the rectangular container cavity, the vortex street driving device does high-frequency vibration under excitation of a low-frequency high-pressure gas, high-frequency vibration is generated bya non-linear magnetic shift cantilever array and a rectangular piezoelectric sheet, and gas pressure energy is converted to electric energy by a positive piezoelectric effect. On the basis of a cylinder turbulence effect, the vibration frequency of a piezoelectric component is improved; by employing a plurality of resonant modes of the cantilever array, the energy capturing bandwidth is expanded,and the energy capturing efficiency of the power generator is improved; and moreover, the multi-mode piezoelectric power generator is simple and novel in structure and has a wide application prospectin the technical field of pneumatics.