The invention discloses a humidifier used for a livestock feeding room. The humidifier comprises a water storage device, a filter device and a humidifier device. The water storage device is connected with a water inlet of the filter device. A water outlet of the filter device is connected with the humidifier device. According to the humidifier, through filtering of a quartz sand filter element, impurities in rainwater can be completely removed, and the water with the impurities being removed enters the humidifier and cannot cause damage to the humidifier; and by adoption of the scheme, the recontamination probability of the rainwater is decreased, the recycle rate of the rainwater is increased, the collected rainwater is reused, energy saving and environment protection are achieved, and multiple purposes can be achieved at one stroke.