The invention discloses a four-wheel steering vehicle rollover prevention system and a control method thereof. The four-wheel steering vehicle rollover prevention system comprises a sensor module, a drive-by-wire rear-wheel steering module, a front wheel differential brake module, a rollover evaluation unit, a route planning unit and a controller ECU; and the sensor module comprises a vehicle velocity sensor, a steering wheel angle sensor, a vehicle body rolling angle velocity sensor, a vehicle body rolling angle sensor, a yaw velocity sensor and an acceleration sensor. The rollover prevention control is carried out through the front wheel differential brake module, and the original driving intention of a driver is kept through the rear-wheel steering module, so that a secondary accident possibly resulting from the traditional rollover prevention control without considering the driving intention is avoided.