Effects of optical parameters on fluid flow and heat transfer of participating magnetic fluid are investigated in this work. Instead of Rosseland approximation, the source term of radiative flux is obtained by solving radiative transfer equation (RTE). In the physical model, all walls of a square cavity are defined as opaque and diffusively reflection. The fluid in the cavity has characteristics of gray, absorbing, emitting, scattering and electrically conducting. The continuity equation and momentum equation are solved by artificial compressibility algorithm based on finite volume method (FVM). FVM is also used to solve the energy equation, and the RTE is solved by discrete ordinates method (DOM) with SSDN quadrature scheme to discretize the solid angle. The results are presented in graphical. Streamlines, isotherms and comparative results of heat transfer rate show the effects of optical parameters on fluid flow and heat transfer. (C) 2012 Elsevier Ltd. All rights reserved.