The invention discloses a backrest angle adaptive adjustment mechanism for a seat of a high-speed railway, the adjustment mechanism comprises a backrest angle limiting mechanism and a reset mechanism,wherein the backrest angle limiting mechanism comprises an angle opening module and an angle locking module; the reset mechanism comprises a reset spring, a pushing plate, a pushing rod, a reset button, a pull rod, a fixing sleeve, a reset sliding block, an adapter ring, a stay wire and a pull ring. The seat in the application enables a passenger in the back row to control the maximal opening angle of the seat in the front row, the comfort of both passengers in the front row and in the back row is taken into consideration; the time of a crew member spent on arranging a train is saved, the efficiency is improved; the crew member can conveniently reset the limiting mechanism from the left side and the right side; the mechanisms in the seat are mechanical structures, the energy is saved, thestructure is reliable, and the maintenance is convenient.