The invention relates to a rearview mirror adjusting system used during travelling of a vehicle. The rearview mirror adjusting system comprises a No.1 relay, a No.2 relay, a rearview mirror motor, an electronic control unit (ECU), a No.3 switch and a steering angle signal, wherein the electronic control unit (ECU) comprises an input end, a No.1 output end and a No.2 output end; the input end passes through the No. 3 switch to be connected with the steering angle signal; the No.1 output end passes through a coil of the No. 1 relay to be grounded; one end of a normally open contact of the No.1 relay is connected with a positive electrode of a power source, and the other end of the normally open contact of the No.1 relay is connected with a positive electrode of the rearview mirror motor; the No.2 output end passes through a coil of the No. 2 relay to be grounded; and one end of a normally open contact of the No.2 relay is connected with the positive electrode of the power source, and the other end of the normally open contact of the No.2 relay is connected with a negative electrode of the rearview mirror motor. Through the adoption of the design of the rearview mirror adjusting system disclosed by the invention, the rear view field during the travelling of the vehicle can be enlarged, so that the situation that traffic accidents are caused due to insufficient view field is avoided; and the rearview mirror adjusting system is easy and simple to handle, high in reliability and reasonable in structure.