Dislocation information and strain-related tetragonal distortion as well as crystalline qualities of a 2-μm-thick InN film grown by molecular beam epitaxy (MBE) are characterized by Rutherford backscattering/channeling (RBS/C) and synchrotron radiation x-ray diffraction (SR-XRD).The minimum yield xmin=2.5％ deduced from the RBS/C results indicates a fairly good crystalline quality.From the SR-XRD results,we obtain the values of the screw and edge densities to be ρscrew =7.0027 X 109 and ρedge =8.6115 × 109 cm-2,respectively.The tetragonal distortion of the sample is found to be -0.27 ％ by angular scans,which is close to the -0.28 ％ derived by SR-XRD.The value of ｜e(⊥)/e‖｜ =0.6742 implies that the InN layer is much stiffer along the a axis than that along the c axis,where e‖ is the parallel elastic strain,and e⊥ is the perpendicular elastic strain.Photoluminescence results reveal a main peak of 0.653eV with the linewidth of 60meV,additional shoulder band could be due to impurities and related defects.