Epitaxial growth of InN films on GaN (0001) by metal organic chemical vapor deposition (MOCVD) was investigated with adding an InGaN bedding layer. It is found that pure InN can be obtained on the InGaN bedding layer with quality higher than on bare GaN surface. By adopting proper In composition (In0.23Ga0.77N in this work) in the InGaN bedding layer, indium droplet formation can be totally suppressed during the growth of InN. The structure and optical properties of InN were investigated by using optical microscopy, high-resolution X-ray diffraction (HR-XRD), transmission electron microscopy (TEM), photoabsorption and photoluminescence at room temperature. From the HR-XRD measurements, the ω and ω-2θ scans show the elimination of In diffraction signal by using the InGaN bedding layer and the ω scan gives a linewidth of 0.23° for 150 nm InN film. From the selective area electron diffraction pattern in the TEM, the InN is found to be almost strain free. Both photoabsorption and strong photoluminescence of InN film at room temperature indicate that the energy band gap of the InN is about 0.74 eV. Abnormal excitation-dependent photoluminescence behavior of the InN was preliminarily investigated too. It is proved that the surface effect of InN materials has a strong effect on the radiation recombination.