This paper studies the nearly degenerate four-wave mixing in plasma which is caused by the electron plasma wave excited via the process of stimulated Raman scattering. The third-order nonlinear susceptibilities of the plasma are derived analytically and the condition to satisfy the phase matching is discussed. The couple-wave equations are solved to obtain the phase conjugate reflectivity. The dependence of the reflectivily on the frequency difference between the pump and the probe beam as well as on the interaction length is studied both analytically and numerically.