Ozone sonde is widely used for in situ measurements of atmospheric ozone profiles from ground to 35 km.In order to obtain the measured precision, sensitivity and reliability of Chinese ozone sonde named GPSO₃, a series intercomparison with Vaisala ECC type ozone sonde has been carried, including the sensitivity and response time of ozone sensors, ozone measurements at ground in comparison with that by a standard ozone analyzer, the pump efficiency at low pressure, and balloon soundings with two sondes together.The results show that our GPSO₃ ozone sensor has the capability similar to that of Vaisala ECC ozone sonde.