The utility model provides a hygrometer which consists of a sampling tube, an intelligence module, a display and data output unit, an meter power supply, a dry ball temperature sensor, a wet ball temperature sensor, a dynamic pressure transducer, a mini draught fan, moisture absorption material, a mini ball float valve, a water receptacle, a water level electrode, and a water replenishing capillary tube. The hygrometer is technically characterized in that the matching of the sampling tube and the mini draught fan can ensure the air current speed flowing through the wet ball temperature sensor, thereby improving the measuring accuracy of the hygrometer. At the same time, the temperature sensor of the intelligent extraction type hygrometer is not influenced by a surface structure, thereby having very good measuring accuracy in the high moisture region. Compared with the hygrometer of a wet-sensitive sensor, the condition that the surface pollution is disabled does not exist, thereby solving the problem that the service life of the sensor is short. The hygrometer has the advantages of high measuring accuracy, wide range ability, long service life, long-time online measure, automatic failure detection, etc. The hygrometer can become a regenerate pioneer product in the environment state parameter measuring technology.