Cryofan is the most vital component for helium closed loop cooling systems, which can provide the circulatory force of the gaseous helium. Thus, it is essential to develop a high efficiency cryofan in order to improve the energy efficiency of the cooling system. In this paper, a cryofan is designed for a helium closed loop cooling system of superconducting magnets. The design inlet temperature and total pressure ratio are 80 K and 1.1 respectively. The design mass flow rate is 17.5 g·s−1. A novel empirical model for incidence loss is proposed to calculate the incidence flow loss. A mean-line design and analysis model based on flow loss models is established to design and predict the performance of the cryofan. Based on the mean-line design results, a 3D design approach is proposed to design the detailed 3D geometry of the cryofan. Furthermore, 3D CFD simulations are conducted in order to predict the performance in design condition and off-design conditions, and further verify the accuracy of the mean-line model. The results indicate that the proposed novel empirical model for incidence loss is accurate and reliable, and an efficient cryofan can be designed and analyzed conveniently through applying the proposed mean-line model and 3D design method.