The invention discloses an automatic separating system and method for an automobile hinge fixing support. The automatic separating system comprises an automatic separation support, a first pre-tightening force spring, a second pre-tightening force spring, a first sliding valve, a second sliding valve, a corner sensor, a base, a motor, a collision sensor and a controller. Under the normal situation, the automatic separation support is stopped through a pin shaft via a base outer shaft inclined shaft and cannot be separated from a base outer shaft; after an automobile is started, the controllercollects signals of the collision sensor in real time; and when collisions of the automobile are judged, the controller controls the motor to drive the automatic separation support to rotate anticlockwise, and then the pin shaft can rotate anticlockwise along the inclined groove in the base outer shaft. When the pin shaft rotates to be aligned with a long groove, horizontal restraints on the pin shaft from the base outer shaft disappear, the automatic separation support moves leftwards by a certain distance under the action of the first pre-tightening force spring and is separated from the base. By adoption of the automatic separating system and method, the problem that an automobile door cannot be normally opened during automobile door or automobile body deformation can be solved.