When guidelines for uncertainty method (GUM) are utilized to evaluate the uncertainty of the pitot tube measuring wind speed, the measurement results often contain deviation. To confirm the applicability of this method and modify the deviation, GUM and Monte Carlo method (MCM) are firstly adopted to evaluate the uncertainty of the measured wind speed. Then, the applicability of GUM is verified by the methods given by JCGM 101:2008 GUM supplement 1. Finally, the wind speed measurement results obtained by GUM and MCM are compared. Results show that GUM method is still suitable for the uncertainty evaluation of wind speed measurement using pitot tube. The standard uncertainty of GUM evaluation results generates a negative deviation. The deviation rate relative to its measured wind speed value is -0611 8×10-5. The modified value is “0611 8×10-5 the measured wind speed value”. This value is smaller than the measured wind speed. For the practical application, it can help decide whether to modify it according to the actual situation.