The h-LuFeO ₃is a kind of narrow band gap hexagonal ferrite material, with a good application prospect in the field of ferroelectric photovoltaic. However, the low polarization intensity of h-LuFeO ₃makes the recombination rate of photogenerated electrons and holes large, which is not conducive to the improvement of the efficiency of h-LuFeO ₃-based ferroelectric photovoltaic cells. In order to improve the ferroelectricity and optical absorption properties of h-LuFeO ₃, the first principles method is used to calculate the doping formation energy values of In atom at different positions of h-LuFeO ₃, and the most stable doping position is determined. The comparisons of band gap, optical absorption performance and polarization intensity among h-Lu _{1- x}In _xFeO ₃( x= 0, 0.167, 0.333, 0.667) are made. With the increase of In doping, the cells of h-Lu _{1– x}In _xFeO ₃stretch along the c-axis. The ratio of the lattice constant c/ aincreases from 1.94 at x= 0 to 2.04 at x= 0.667 when all the positions of In replace P1 position. Using the qualitative calculation of Berne effective charge, the results show that the ferroelectric polarization intensity of h-LuFeO ₃, h-Lu _0.833In _0.167FeO ₃, h-Lu _0.667In _0.333FeO ₃and h-Lu _0.333In _0.667FeO ₃along the c-axis are 3.93, 5.91, 7.92, and 11.02 μC·cm ^–2, respectively. Therefore, with the increase of the number of In atoms replacing Lu atoms, the lattice constant c/ aratio of h-Lu _{1– x}In _xFeO ₃increases, which can improve the ferroelectric polarization strength of the material. By analyzing the density of states of h-LuFeO ₃and h-Lu _0.333In _0.667FeO ₃, we can see that In doping enhances the Fe-O orbital hybridization in h-Lu _0.333In _0.667FeO ₃, and makes the optical absorption coefficient of h-Lu _0.333In _0.667FeO ₃in the solar light range larger. In summary, In doped h-LuFeO ₃is an effective method to improve its polarization intensity and optical absorption coefficient, which is of great significance for improving the performance of ferroelectric photovoltaic.