The effective potential energy curves correlated to 2I03/2 and 2I01/2* atom limits are calculated using second order spin-obit multiconfigurational quasidegenerate perturbation theory (SO-MCQDPT). The absorption spectra of CH3I molecule are calculated, photodissociation processes of CH3I molecule are analyzed and the quantum yields of 2I01/2* atom are estimated. The present calculations can be used to interpret the experimental results.