Abstract: The conjugated heat transfer of natural convection in pool with internal heat source and the forced convection in the tube was analyzed,and the corresponding three-dimensional physical and mathe-matical model was proposed.A control volume based finite element method was employed to solve numeri-cally the problem.The computations were performed for different internal heat source intensity of the pool and the different flow velocity in the tube.The computed heat transfer coefficients on the inner and outer wall showed well consistency of those calculated with the empirical correlations.Compared with the measured total heat transfer coefficients between the fluids in and out of the tube,the computed ones showed also the well consistency,which implied that the numerical model proposed in this paper was reliable.The research results revealed that the total heat transfer coefficients between the fluids were strongly affected by the inter-nal heat source intensity of the pool liquid and the flow velocity in the tube.