The invention relates to a preparation process flow of a micro electric field sensor with a cantilever beam structure, which is carried out sequentially according to the following steps of: etching asilicon substrate material to form an alignment mark; heating a silicon wafer; depositing a piezoelectric thin film PZT; carrying out patterning etching; releasing a silicon wafer ohmic contact region; evaporating a metal electrode; etching a cantilever beam; implementing a thinning process on the bottom of the silicon wafer; carrying out patterning etching on the thinned bottom of the silicon wafer; bonding a base; and carrying out scribing on the machined wafer. The preparation process flow has the beneficial effect of ensuring stability and durability of a sensing device.