Seat backrest angle adjusting mechanism

The utility model provides a seat backrest angle adjusting mechanism aiming at the defect that in the prior art, the service life of a locking and fixing scheme that a connecting piece is locked and fixed through the elastic effect of a spring is short, and belongs to the technical field of seats, and the seat backrest angle adjusting mechanism comprises a base, a cushion installation seat and a backrest installation seat, a sliding pair is arranged between the cushion mounting seat and the backrest mounting seat, and a slider-crank mechanism is formed among the base, the cushion mounting seat, the backrest mounting seat and the sliding pair; a transverse shaft is arranged on the cushion mounting seat, a pull rod which is always parallel to the transverse shaft is arranged on the base in a sliding manner, a connecting piece transmission assembly is movably arranged between the pull rod and the transverse shaft, and a pressing assembly used for locking the connecting piece transmission assembly and an operatin