We investigated the optical and electrical properties of Mg-doped InxGa1-xN(0≤x≤0.3) grown by metalorganic chemical vapor deposition with different In and Mg contents. When the Mg doping concentration was fixed, the hole concentration of samples increased remarkably with the elevation of In mole fraction. The highest hole concentration achieved was 2.4×1019cm-3,the doping efficiency increased nearly by two orders. We explained the carrier transition mechanism with the help of the photoluminesce spectra. In addition, we obtained the activation energy of Mg and the band position of deep donor in InGaN:Mg samples.