A piezoelectric energy generator with a Deflection-limiting Circular Arc (DLCA) was presented to enhance its generated energy and reliability. The structure and working principle of the piezoelectric generator were introduced and an energy conversion model for the piezoelectric generator was established.By simulation, the influence of thickness ratio of the substrate thickness to the total thickness of the piezo-cantilever on the minimal radius of DLCA as well as the generated energy, and that of total thickness of the piezo-cantilever and the radius of DLCA on the generated voltage as well as electrical energy were obtained. The analytical results show that the minimal radius of the DLCA decreases linearly with the increasing of thickness ratio, and there is a shared optimal thickness ratio(0.35) for piezoelectric generators with different total thicknesses to achieve maximal output voltage and energy. Several piezoelectric generators with different radii of DLCA were fabricated and tested. The results show that the maximal voltage (displacement) of the piezoelectric generator depends mainly on the radii of DLCA. When a minimal radius of DLCA is set, both the maximal electrical energy and higher reliability can be achieved.