In this study, a cooling system composed of a double-entry centrifugal fan and a longitudinal- plate heat sink is investigated. The fan-sink assembly is popular for cooling the device of a notebook and some electronic systems. Due to the complexity of their coupling, the performances of a fan and a heat sink are investigated separately in the literature. Thus the overall cooling mechanism and the best cooling efficiency of the system have not been revealed. However, the coupled cooling system composed of a fan and a heat sink is investigated together. For the accuracy of CFD analysis, the overall flow field is investigated by implementing the κ–ε turbulent model. The optimum coefficients of the turbulent model are determined by comparing the numerical results and the experimental ones. Moreover, the influence of parameters of fin on the performance of the cooling system is investigated.