The invention relates to a buffer device for diminishing pressure pipeline fluid pressure pulsation, belonging to the technical field of pipe fittings, for solving the issue of controlling fluid pressure pulsation. The buffer device comprises a pressure container body two ends of which are semi-spherical end sockets, and the middle of which is a hollow cylindrical drum; the top of a semi-spherical end socket at one side of the pressure container body is provided with a liquid inlet; the hollow cylindrical drum close to the liquid inlet side is provided with a liquid outlet; the hollow cylindrical drum is provided with a pore plate internally; the pressure container body is divided into a large chamber and a small chamber by the pore plate; the liquid inlet and the liquid outlet are all positioned at the small chamber; the liquid inlet and the liquid outlet are respectively connected with a liquid inlet pipe and a liquid outlet pipe, wherein the liquid inlet pipe penetrates through the pore plate and extends towards the middle part of the pressure container body. Through the buffer device provided by the invention, a three-way structure of the original energy accumulator is changed, the unevenness of the pulsation fluid pressure is weakened fully, and further the fluid pulsation in the pipeline is diminished radically; and the fluid pulsation in a pipe system is decreased fully, and the safe and stable operation of the system is ensured.