Wurtzite (w) and zincblende (zb) InN films have been grown on (011) SrTiO3 (STO) substrates by metal- organic chemical vapor deposition, the epitaxial relation- ships and optical properties are characterized by X-ray diffraction (XRD), absorption and photoluminescence (PL). Based on XRD θ –2θ  and  Φ  scanning results,  the  epi- taxial relationships between (w- and zb-) InN films and STO substrates are determined, that is, (0001)[1120]w-InN (011)[100]STO and (100)[011]zb-InN //(011)[100]STO. Compared with the w-InN films, the zb-InN films exhibit a red shift in absorption edge and PL spectra, and a much nar- rower and stronger PL spectrum, implying a better optical quality of zb-InN films. The structure transition is supposed to be due to the difference in atom and bond areal density between the crystal plane of w-InN(0001) and zb-InN(100).