The invention discloses a piezoelectric cantilever vibration energy harvester and a preparation method thereof, belonging to the technical field of micro electro mechanical system (MEM). The harvester comprises an upper cantilever, a lower cantilever, a mass block and a fixing device, wherein the mass block is arranged at one end of the lower cantilever, and the fixing device is fixed at the other end of the lower cantilever; the upper cantilever is arranged on the mass block and the fixing device and is symmetrical with the lower cantilever; the mass block and the fixing device are respectively and fixedly connected with the upper cantilever; distance from the fixing device to the mass block is L; the upper cantilever comprises a first support layer, a first lower electrode layer, a first upper electrode layer and a first PZT layer; the lower cantilever comprises a second support layer, a second layer electrode layer, a second upper electrode layer and a second PTZ layer; and the support layer comprises a first SiO2 layer, an Si layer and a second SiO2 layer. The invention improves mechanical transformation ability, can collect more electrical energy from mechanical vibration, has controllable preparation method and improves the production success rate of the devices.