The Pitot tube is the main standard device of the wind calibration facility, whose measurement accuracy is important for calibration quality. From the measurement principles of Pitot tube, the factors influencing the measurement errors of Pitot tubes are introduced in detail. The measurement deviation causing by these influence factors is simulated. The main influencing factors of measurement errors of Pitot tubes are analyzed.The results show that the temperature and obstruction coefficients are the main factors to produce measurement errors for second class Pitot tubes.When the deviation of environment temperature reaches ±8℃, the wind error of the Pitot tube is 044 m/s (〖WTBX〗v〖WTBZ〗=30 m/s).When the deviation of obstruction coefficient reaches ±002, the wind error of the Pitot tube is ±06 m/s (〖WTBX〗v〖WTBZ〗=30 m/s). The effects of the Pitot tube coefficient, pressure, and humidity are smaller.