The upgrading and reconstructing of the calibrating system based on the Model500 windtunnel used widely in the provincial/prefecturallevel meteorological instrument calibration departments is introduced. The overall design scheme and philosophy are based on a computer, and the data collector and motor control circuit are developed to digitize all physical quantity involved in the process of calibration. The computer reads in data from the asynchronous serial port of the collector to realize the automation of AWS (Automatic Weather Station) wind speed sensor calibration and meanwhile to have the capability of calibrating semiautomatically conventional windfinding instruments. The calibration data are put into the LAN server, and the remote processing, printing, and sharing of data are realized. The software is based on the Windows platform written by VB 6.0. This system has been put into operation, and the practice of more than one year proves that it is steady, reliable, and easy to use. The competent authorities plan to popularize the system in the meteorological instrument calibration agencies across China.