An optical translational projector (OTP) designed by transformation optics is applied to improve the energy transfer efficiency in a wireless energy transfer (WET) system. Numerical simulation results show our OTP can greatly enhance the energy transfer efficiency (e.g. nearly 2 orders, compared to the case without our OTP) in WET systems, which is much larger than previous methods (e.g. magnetic super-lens). A 3D reduced OTP composed by layered isotropic magnetic materials is designed, whose performance has been verified by 3D numerical simulations in 10MHz. We also study the influence of loss of metamaterials on the performance of proposed OTP.