In this study, a hierarchical structured control system which consists of a main-loop and a servo-loop controllers is designed to enhance the handling and stability of an all-wheel independently driven Electric Vehicle (EV). In the main loop, a Fractional Order PID (FO-PID) based controller is proposed to generate desired external yaw moment. A modified Differential Evolution (M-DE) algorithm is adopted to adjust the controller parameters. The desired external yaw moment is optimally distributed to individual wheel torques in the servo loop by using a Sequential Quadratic Programming (SQP) approach, with the tire force limits estimated by Unscented Kalman Filter (UKF). The EV prototype is modelled in Adams/Car, validated by experimental data, and serves as control plant. The feasibility and effectiveness of the designed control system are examined by simulations.