At this stage because most areas of the wind tunnel hardware and software conditions are limited , accuracy of 30, 40 and 70 m/s wind speeds for AWS wind speed sensors can not be verified, so that the accuracy and reliability of high wind speed data can not be guaranteed in these areas. In order to solve this problem, In this paper, the method of linearly extending the test data of low wind speed section to high wind speed section is proposed. Based on the physical principle of the threecup wind speed sensor, the feasibility of the method is proved by theoretical analysis and experimental verification, So as to solve this practical problems. The method provides a strong theoretical basis for making new test specification of the wind speed of Automatic meteorological station.