A new Simpson gearset based dual motor powertrain (SGDMP) is proposed to improve the energy efficiency of electric vehicles (EVs). The Simpson gearset consists of two planetary gearsets and a brake. Two motors are connected to sun gear and ring gear of the first planetary gearset, respectively, while the carrier of the second planetary gearset connects to the output shaft. SGDMP can realize four driving modes that are two single motor driving modes, a speed coupling driving mode, and a torque coupling driving mode, by changing the working states of brake and motors. The key parameters of powertrains are designed by minimizing the peak power of motors and satisfying the requirements of dynamic performance. The single motor with 2-speed transmission (SM2T) having the same dynamic performance is employed as the references to show the economic performance of SGDMP. The mode selection strategy of SGDMP are formulated by optimizing the consumed power of motors. The simulation results under five typical driving cycles demonstrate that SGDMP can improve the economic performance.