In order to solve the problem of lack of correlation analysis between the components of uncertainty when the air pressure sensor of automatic weather station used GUM to evaluate the uncertainty in the past.This paper takes PTB210 digital air pressure sensor as the research object, designs the corresponding laboratory calibration scheme according to the verification regulation of air pressure sensor, and calculates its corresponding measurement model.On the premise of analyzing the correlation between its uncertainty components, the corresponding uncertainty evaluation method is developed.By implementing this method, the combined standard uncertainty of forward stroke and reverse stroke is 0.065hPa and 0.069hPa respectively at 1010hPa calibration point.This method is more close to the reality, and the result of uncertainty evaluation is more real and reliable, which can effectively make up for the shortcomings of GUM in evaluating the uncertainty of air pressure sensor in the past.