We report optimized geometrical structures at the RHF/6-31G* and 3-21G levels, the properties of excited states using time-dependent density functional theory based on the B3LYP/3-21G* level, and the frequency dependence of third-order nonlinear optical polarizabilities gamma in different optical processes of THG, EFISHG, and DFWM by using B3LYP coupled with the sum over states methods (SOS//TDDFT-B3LYP/3-21G*) for the MPcCl (M = Al, Ga, In) molecules. The calculated results show that both the distance of the central atom from the Pc plane and the gamma value increase in the order of AlPcCl < GaPcCl < InPcCl. The dispersion behaviors of the three different optical processes are discussed, and the calculated susceptibilities of chi((3))(-omega; omega, omega, -omega) match the measured values and correspond to the varied trends in the measurements of AlPcCI < GaPcCl < InPcCl films. It is found that a large ionic radius of M makes a large distortion away from C-4upsilon symmetry and that a larger d-electron transfer results in a red shift in the absorption spectrum and a large third-order nonlinear optical susceptibility among the MPcCl (M = Al, Ga, In) materials.