Through releasing three sets of radiosonde tied by a same balloon, the performance of the Finland Vaisala sounding system was tested. The results indicate that the consistency of pressure and humidity is in accordance with the technical specifications of RS92 GPS radiosonde, so is temperature except in the 10 hPa layer in the daytime; humidity and wind meet basically the requirements of WMO for the GCOS (Global Climate Observing System); geopotential height can well satisfy the WMO GCOS requirements. The analysis of the radiative characteristics shows that the influence of solar radiation is small below 70 hPa and great above 20 hPa. The experiment suggests that the radiosonde can also sensitively detect humidity with good measuring performance within clouds; the coordination between temperature and humidity is reasonable; the data losses of RS9GPS2 are significantly less than those of RS80, but improvements are still needed in stability, examination and software.