The invention discloses a Hall-sensing-based adjusting method of an automobile headlamp adjusting system. The automobile headlamp adjusting system comprises a headlamp body, a step motor, a first Hallsensor, a second Hall sensor, a light intensity sensor and a control module; the step motor is used for adjusting horizontal irradiating angle of the headlamp body; the first Hall sensor and the second Hall sensor are arranged on left and right front wheels of an automobile respectively. During operation, the control module controls on or off of the headlamp body according to sensing data of thelight intensity sensor, calculates a horizontal defection angle of the headlamp body according to sensing data of the first and second Hall sensors upon turn-on of the headlamp body and then controlsthe step motor to adjust the horizontal irradiating angle of the headlamp body. The Hall-sensing-based adjusting method of the automobile headlamp adjusting system has the advantages that the design is simple, the method is convenient to use, the irradiating direction of the headlamp is automatically adjusted when an automobile makes turning, visual blind area is eliminated for a driver, and safety is improved.