The HMP45D humidity sensor, an integrated temperature and humidity measuring device, is used widely across China. Because of the vast territory of China, there exists big difference in the environment temperature from south to north, especially in cold seasons. At some stations in the furthest North, temperature can be as low as －40 ℃. In order to understand the influence of environment temperature on the measuring accuracy of humidity, a characteristic experiment was conducted. Three humidity sensors were randomly selected as testing sensors and the output humidity values of the doublepressure humidity generator were used as standard humidity values. Under the different temperature conditions, the testing of the influence degree of temperature on the measuring accuracy of humidity was carried out.