The invention discloses a device and a method for automatically separating, collecting and reutilizing urine and relates to an agricultural environmental engineering technology. The device consists of a urine water (urine and wash water) automatic separation and collection system, a urine reutilization system and a gray water (wash water) treatment system, and an automatic control technology, an environmental pollution control technology, a technology for recovering and reutilizing nutrient substances, such as N, P and the like, and the like are involved. According to the device and the method, gray water load can be reduced to a great degree; environment is effectively improved; domestic sewage can be reutilized; nutrient substances such as N, P and the like can be recycled; waste of resources is avoided; and a certain economic benefit is achieved. The method is easy to implement, low in cost, and high in applicability and has strong use and popularization demonstration value.