The invention relates to a rearview mirror following-up performance detection device and method. An automobile body control module of the rearview mirror following-up performance detection device is respectively connected with a steering wheel angle sensor, a turn light controller, a rearview mirror controller, a detector and an indicator. The automobile body control module controls the rearview mirror to rotate at a certain angle according to input signals of the steering wheel angle sensor and the turn light controller, so a monitoring range of an automobile driving in a curve or changing lanes can be enlarged; and relative position information and relative speed information between an object behind the automobile body and the automobile can be acquired by the detected, so a relative operation indicating signal can be given to an automobile operator. By the use of the rearview mirror following-up performance detection device, the monitoring range is enlarged when the automobile drives in a curve or changes lanes; a view dead zone of the automobile driver can be narrowed; and possibility of accident occurrence can be reduced.