This thesis studies the software design of a reference-based ESC system in instability detection and stabilizing torque allocation and proposes a modification to the original sideslip angle deviation control. It is replaced by a sideslip angle–sideslip angle velocity phase map. By introducing sideslip angle velocity as an additional dynamic variable, the controller can consider not only the magnitude of the sideslip angle, but also its changing tendency. This allows the ESC logic to make a more continuous and physically meaningful judgement of vehicle stability.