Identifying strong third-order nonlinearities and low nonlinear optical losses, including photonic crystals and plasmonic structure^1–4, are crucial for developing optoelectronic devices and nanophotonics technologies. We presented large enhancement of degenerate two-photon absorption through hexagonal cavity resonance in single-crystalline ZnO microwire involved Fabry-Perot (FP) cavity and whispering gallery mode (WGM) cavity. We reported it is feasible to fabricate degenerate two-photon absorption single microwire photodetector. The device photocurrent performed a typical parabola curve with the increasing of incident irradiance due to third-order nonlinearity. We experimentally demonstrated two-photon absorption enhancement resonated in WGM cavity is more excellent than that in FP cavity for the highly confined optical fields ability at room temperature.