In the verification process of the humidity sensor, in addition to the uncertainty of verification results caused by the dewpoint meter and temperature and humidity box, the verification conditions and nonstandard operation will also bring additional errors to the verification results. In this paper, the standard deviation of the measured value at each humidity point of the dewpoint meter, the thermal effect of the dewpoint meter during operation, the flow change of the sensor skimming the dewpoint meter, and the optimum working environment of the dewpoint meter are tested. Combined with the historical data of the humidity sensor test, a comprehensive analysis is made to draw the following conclusions: (1) When the flow hole of the dewpoint sensor is facing the airflow direction, the dewpoint temperature measured at the same temperature is higher, and the relative humidity measured by the dewpoint sensor is smaller. Otherwise, it will be larger. (2) When the ambient temperature is 20 ℃, the standard deviation (discreteness) of the measurements of the dewpoint meter at each humidity point is minimum. (3) When the temperature sensor of the dewpoint meter in the suction type temperature and humidity box is installed at 4 cm the front end at 4 cm the back end, the measured value of its rear end is 0.45 ℃ higher than the maximum value installed at the front end, and the relative humidity is 0.5% higher. (4) The stability time at each humidity point (when the humidity in the box reaches the set value and tends to be stable) should be greater than or equal to 20 s, the standard value and measured value collected by the dewpoint meter and humidity sensor under inspection are true.