A method for manufacturing an energy harvester including a piezoelectric polymer microstructure array. The method includes: preparing a micro-column array of a piezoelectric polymer on a substrate; supplying a plate electrode as an upper electrode, allowing the substrate and the upper electrode to form a pair of plate electrodes; applying a DC voltage between the pair of the plate electrodes; heating the substrate to a temperature higher than a glass transition temperature of the piezoelectric polymer and performing rheological formation of the micro-column array with the DC voltage still being applied until the column array of the piezoelectric polymer reaches the upper electrode to form a mushroom-shaped structure array; and cooling and solidifying the piezoelectric polymer to obtain the piezoelectric energy harvester.