The radiation effect on the thermophoresis of particles is analyzed for a gas-particle two-phase laminar flow, Two-phase radiation by both gas and particles is considered; in addition, the thermal nonequilibrium between gas and particle is taken into account. It is concluded that the particle diffusion velocity as well as particle concentration depends strongly on the optical radius of gas or particle. In general, the radiation was found to decrease the particle diffusion. In case that gas as well as particle radiation exists, the deposition of particle is mainly influenced by the gas. The effects of parameters such as the optical radius, conduction to radiation parameter, thermal loading ratio, and wall emissivity on the cumulative collection efficiency E(x) are also considered. As the optical radius and tube wall emissivity increase, E(x) decreases. The increase in conduction to radiation parameter N and thermal loading ratio C-L leads to an increase in E(x).