Abstract Heat sources on rectangular plate with convective cooling at both upper and lower surfaces are common heat transfer application case in electronic packaging. In this paper, in order to find the analytical solution for this problem, a thermal resistances network model was established based on heat flux flow distribution. The model was used to calculate thermal resistance and predict the mean temperature of the heat source. Simulations by commercial software COMSOL3.5 provided a reference for verification of the model. Data comparisons between simulation and analytical solution show that the network model is accurate to calculate the thermal resistance of the discussion cases and the maximum relative error is 3.47%.