Abstract: The electrochemical concentration cell (ECC) type ozone sonde, developed by Institute of Atmospheric Physics(IAP), Chinese Academy of Sciences(CAS) is tested through indoor basic examinations and outdoor flying comparison observations with imported ECC ozonesondes. Indoor tests for IAP ozone sonde include the sonde background current (I_bg), the response time and the influences of SO₂ and NO₂ on ozone measurements, and the low pressure pump efficiency (C_ef). Results show that I_bg is less than 0.1 μA and it decreases with the growth of altitude. The response time is 21-26 s. Ozone concentration is much underestimated/overestimated as SO₂/NO₂ gas is input to the ozone sonde. C_ef is about 1.0 as the atmospheric pressure is more than 100 hPa while it rises with the decrease of atmospheric pressure, reaching 1.17 ±0.10-1.28 ±0.16 as the pressure is 10 to 5 hPa. C_ef of IAP ozonesonde is higher than that of imported products with the value of about 1.055. Outdoor comparison observation shows that IAP and imported ozonesonde have good compatibility in the radiosonde platform and sampling pumps. The ozone vertical profiles from each sonde show generally consistent with each other. The ratio of total ozone measured by IAP ozonesonde to that from Brewer observations is 0.9-1.1. Ozone concentration difference is effectively reduced in the lower stratosphere when C_ef and I_bg of IAP ozonesonde is used. Applications of C_ef and I_bg of IAP ozonesonde contributed to 15 DU and 4-6 DU column ozone. The mean absolute difference of tropospheric ozone partial pressure are stable and its values are less than 0.5 mPa, and the stratospheric difference doesn't exceed 1.0 mPa, although the impact from the pump on IAP ozonesonde is obvious. An international low-pressure environment simulation cabin comparison test is necessary for IAP ozonesonde. The stability of C_ef of this radiosonde system should be improved, and it suggests that filtering algorism should be added to data depressing (including meteorology and ozone processing) to decrease data oscillations.