The invention discloses an auxiliary scanning device for firearm aiming and belongs to the technical field of tactic investigation equipment. The auxiliary scanning device for the firearm aiming comprises a controller (1), an alarming module (2), a power source module (3), an ultrasonic ranging module (4), an infrared sensing module (5), a motor control module (6) and a motor (8). The controller (1) is electrically connected with the ultrasonic ranging module (4), the infrared sensing module (5) and the alarming module (2). The power source module (3) provides electric energy for the controller (1), the ultrasonic ranging module (4), the infrared sensing module (5), the alarming module (2) and the motor control module (6). Compared with the prior art, the auxiliary scanning device for the firearm aiming has the characteristics of being simple in structure, reliable in property, high in stability, high in combat effectiveness and the like.