Measurement uncertainty is a parameter that shows the credibility of calibration results. In order to ensure that the results of pressure sensors are correct and reliable, according to the requirements of the Standards JJG (meteorology) 001 2011 Pressure Sensor of Automatic Meteorological Station and JJF 10591 2012 Evaluation and Expression of Uncertainty in Measurement, using the MODEL 745 pressure calibrator as a standard device to calibrate a Vaisala PTB220 pressure sensor, a mathematical model is built, and the uncertainty sources, 〖JP2〗which have significant effects on the measurement results, are analyzed and listed. The pressure sensor test is conducted, and the uncertainty of its calibration results (02 hPa) is analyzed. The uncertainty evaluation method is of significance and reference value to other kinds of sensors.