A facile approach to prepare ZnO with various microstructures was reported using oleylamine as capping agent and surfactant. The structures and morphologies of the prepared ZnO were characterized by XRD, SEM, TEM, FT-IR, UV-vis diffusion reflection spectra (UV-DRS), photoluminescence (PL) spectra, Raman spectra and BET. Furthermore, uniform conical column-like, brush-like and cauliflower-like ZnO microstructures were successfully prepared by tuning the molar ratio between oleylamine to zinc acetate. The results suggested that oleylamine played a significant role in controlling the evolution of these new morphologies. The influence of the molar ratio between oleylamine and zinc acetate was systematically investigated. A growth mechanism was proposed to explain the formation of ZnO microstructures. The photocatalytic performances of the prepared ZnO with different morphologies were evaluated by the degradation of methyl orange (MO) under UV light illumination.