In order to enhance the output pressure of the piezoelectric pump, combined with the working characteristics of multichamber in series connection pump, using an umbrellashaped checkvalve, a stacked in series connection fourchamber piezoelectric pump was designed. The design had compact pump in structure, shorter flow channels inside the chamber, smaller geometry volume, and other advantages. The output flowrate and pressure of the in series connection fourchamber piezoelectric pump were tested by drived under piezoelectric vibrators of different numbers. The results show that the output flowrate drived by multipiezoelectric vibrators is about times as much as drived by sigle piezoelectric vibrator (n is the number of vibrators). When driven by 2 or 3 vibrators, the output pressure is about times. When powered by 110 V AC drive voltage, the maximal output flowrate and pressure of the designed pump are 980 mL/min and 123 kPa respectively.