A self developed hypobaric chamber and its technological parameters, as well as the performance tests and preliminary application, are introduced. The chamber is cylindrical shaped with the dimension of 600 mm in length and 550〖CD*2〗600 mm in diameter. The internal pressure of chamber can be reduced in an automatic or manual mode, and the lowest value can be 21 hPa. Performance testing results show that the average pumping rate of the chamber is 41 hPa/s. The logarithm of pressure in chamber varies linearly with suction time within effective pressure range. The chamber pressure response curve decreases with decreasing pressure, and the average deflation rate of the chamber pressure is 66 hPa/s. The deflation efficiency maximum value is around 100 hPa, with the efficiency reducing from 100 hPa in the higher or lower direction. The static response tests show that the chamber air pressure variability is 22% to 36% in 10〖CD*2〗60 s, and 36±18% in 1〖CD*2〗10 min. The average air leak rate of the chamber is 04 Pa/min in 10 min, and the actual pressure deviations in 10, 20, 40 min and 1 hour is 004, 01, 019, and 025 hPa, respectively. The hypobaric chamber is used for testing the SPC 6A ozonesonde pump efficiency in a low pressure environment. The results show that the deviation of pump efficiency correction factor is <25%, <5%, <6%, and <5%, 〖JP2〗respectively, when the corresponding air pressure is >70 hPa, 70〖CD*2〗35 hPa, 35〖CD*2〗20 hPa, and <20 hPa. These measured pump efficiency correction factors are consist with the original values provided by the manufacture. The hypobaric chamber is expected to provide a low pressure environment for correlative meteorological instrument performance testing.