Seat backrest adjusting mechanism

The utility model relates to a seat backrest adjusting mechanism, a seat backrest frame and seat armrests, wherein the seat backrest frame and the seat armrests are arranged on a seat rotating stand. The seat backrest adjusting mechanism is characterized in that the seat rotating frame is provided with a backrest pull rope, an air spring and a sliding device; the sliding device is provided with a hinge; and the hinge and the end part of the air spring are connected with the seat backrest frame. When in operation, control buttons arranged on the armrest are pressed, the front end of the air spring is pulled by the pull rope, the air spring is unlocked, and the backrest can be inclined downward with a certain angle; and simultaneously, due to the effect of a hinge assembly connected on the sliding device, the hinge assembly is inclined similarly, so that the rear end of the cushion is inclined downward by a corresponding angle. Therefore, the seat backrest adjusting mechanism leads passengers to be more comfort