The modified Becke-Johnson (MBJ) exchange potential together with correlation part of M06 Minnesota functional was used to obtain accurate band structure profile for AlxIn1-xP ternary semiconductor alloy. The effective band structures of alloys were calculated using spectral weight approach, and the composition dependence of the fundamental gap energy, critical point energies and electron effective masses were estimated from the weighted average of effective band structures. The results of the supercell calculations for energy gap and bowing parameter are in good agreement with experiments. The results also show that crossover point of (C-C) direct to (C-x) indirect gap energies occurs at x = 0.48, which is consistent with experimental findings. Furthermore, our results show that the combination of MBJ exchange and M06 correlation potential can be used to estimate accurate band structure profile for AlP, InP, and their alloys.