In order to improve output gas capability of piezoelectric pump, a threechamber gas piezoelectric pump in parallel with passive check valve was designed and manufactured. An umbrellashaped rubber valve with small opening pressure and better check effect was used in piezoelectric pump. The output gas flowrate was experimentally measured. Test results show that the best output effect is when three vibrators are driven synchronously. Comparing testing data with the theoretical calculation value of output flowrate, the results show the two data are very close within operating frequency range of 40~400 Hz. The maximum output gas flowrate is 4 000 mL/min when powered by 110 V drive voltage. The test results provide reliable data to understand the characteristics of threechamber gas piezoelectric pump in parallel.