Automobile seat backrest backward tilting risk avoiding device and method

The invention discloses an automobile seat backrest backward tilting risk avoiding device and a risk avoiding method. The risk avoiding device comprises a seat angle adjusting part, a transparent detection part and a safety belt control part, wherein the seat angle adjusting part includes a ratchet wheel and a clamping jaw, one is installed on a backrest of an automobile seat, the other one isinstalled on a seat of the automobile seat, and after backward pressure borne by the backrest exceeds preset pressure, the ratchet wheel and the clamping jaw can relatively rotate to adjust the angleof the backrest; the transparent detection part is arranged on a back surface of a windshield of the automobile, and after the transparent detection part is pierced, the transparent detection part detects and outputs a danger signal; and the safety belt control part receives the danger signal and makes the safety belt be locked so as to drive the backrest and the corresponding passenger to tilt backwards to avoid danger. Acco