The invention discloses a piezoelectric and triboelectric coupling-based flexible micro energy harvester. The energy harvester comprises a piezoelectric layer, first electrode layers, second electrode layers, friction layers and substrate layers, wherein the first electrode layers, the friction layers, the second electrode layers and the substrate layers are arranged on the upper and lower sides of the piezoelectric layer from inside to outside in sequence; the friction layers comprise bumps with micron-scale structures. The invention also provides a corresponding preparation method. Each metal electrode layer and each metal compound layer are obtained from flexible piezoelectric materials such as PVDF (Polyvinylidene Fluoride) obtained through a spin coating, deposition or electrostatic spinning process by using processes such as sputtering, spin coating and evaporation, the flexible polymer bump static friction layer is prepared by using a molding method, meanwhile, a flexible substrate polymer is adopted and a piezoelectric and triboelectric principle is combined to manufacture the micro energy harvester of a hamburger structure stacked by central piezoelectric layers. The device has the characteristics of simple structure, easiness in implementation of micro machining, variable size, wide frequency band, high conversion efficiency and the like.