Abstract: We develop a theoretical model to study density of state mass dependent Optical Phase Conjugation via Stimulated Brillouin Scattering (OPC-SBS) in direct gap semiconductors. An empirical formula based on phenomenological model is used to determine the maximum possible plasma density in terms of density of state mass in the medium which is used in deriving third order susceptibility using coupled mode scheme and hydrodynamical model. Extensive numerical estimates have been performed to appreciate the DOS dependency of OPC process in InSb, CdS and GaAs crystals shined by119 pulsed laser at 300K. Threshold value of pump electric field, the possibility of optical phase conjugation and the corresponding interaction length is to be premeditated. The maximum possible plasma density is found to be highest in CdS and lowest in InSb crystals. Hence the analysis reveals that higher the density of state mass lower is the interaction length. CdS is found to be most appropriate host for the (OPC-SBS) process with highest gain coefficient and with lower interaction length. On the other hand if the crystal is used as an optical waveguide with relatively large interaction length then InSb proves its potential in practical applications such as fabrication of phase conjugate mirrors.