The invention relates to a micro-type dynamic piezoresistive pressure sensor and its making method, using MEMS silicon bulk micromachining method to make a pressure sensitive chip of E-shaped silicon cup structure, the reverse side of the chip is welded with static seal technique, Pyres glass ring and Hitachi alloy ring, to form silicon back contact medium quasi-level packaging, the reverse back of the chip is covered with anti-interference insulating layer, the right side of the chip is connected with a lead cable through connecting circuit, the sensor tube cap with cable drawing-off mouth at the tail is hermetically welded to the Hitachi alloy ring to form sealed isolation between the side pressure surface and the back pressure cavity, the tail of the tube cap squeezes tightly the cable without sealing, the nozzle part of the sleeve covered on the cable is hermetically covered on the tail of the tube cap, the heat-shrinkable tube segment covered on the cable is hermetically fixed with the outer end part of the sleeve nozzle, thus implementing atmosphere connection between the back pressure cavity and the measured environment, and it is used in shrinkage mould test for hydraulic engineering like dam, ship gate, pier, embankment, etc. and has low measuring range, high sensitivity, strong anti-interference performance, and good dynamic performance during fluid dynamic test.