Abstract: A single hole cylindrical high frequency response pressure probe characterized by high frequency,small size,high accuracy and reliability has been developed for rotor flow measurements in a high speed multistage fan.With the help of a two axes traverse mechanism and a high speed data acquisition and processing system,the periodic two dimensional flow field at the exit of the third rotor of the fan has been successfully measured by using an on line calibration technique to determine the pressure sensitivity and null pressure reading (zero offset) during the compressor measurements.The results with the high accuracy and fine resolution provide an important basis for redesign of the third stage.Furthermore,the probe,measuring method and data reduction procedure are proved simple,precise,practical and reliable.