Applying wireless power transfer technology is one of effective approaches for conducting mobile DC emergency protection. The main work of this paper is to propose a ferrite core design and optimization method for mobile DC emergency wireless power charging module, which can further improve the misalignment tolerance between the transmitter and the receiver and reduce the core loss. The optimized design is developed to maintain uniform magnetic flux density in the core and to minimize the core loss. Considering the misalignment error between the transmitter and the receiver when the car is parked, the magnetic flux density will change. Therefore, the misalignment error and the misalignment direction probability should be further optimized. After comprehensive consideration, the optimized structures of the circular and bar cores are finally designed, and a continuous nonlinear programming optimization algorithm in FEA is proposed to make the flux density distribution uniform. It is verified that compared with the original magnetic core structure, the core loss per unit volume of the optimized circular core is reduced by 30%, and the core loss per unit volume of the bar core is optimized by 39%. Moreover, the optimized circular core can reduce the volume of the core loss per unit by 17.5%.