The invention belongs to the field of composite materials, and specifically relates to a water-absorbing rubber composite material and a preparation method thereof. The water-absorbing rubber composite material comprises the following components by mass: 100 parts of raw rubber, 10-60 parts of water-absorbing resin, 1-45 parts of a water-absorbing aid, 0-6 parts of zinc oxide, 0-2.5 parts of stearic acid, 0.5-3 parts of a vulcanizing agent, 1-5 parts of a vulcanization accelerator, 0.5-3 parts of an anti-aging agent, 10-50 parts of a reinforcing agent, 5-40 parts of a filler, 5-30 parts of a softener and 3-5 parts of a pigment. The water-absorbing rubber composite material is finally vulcanized and molded in a manner of mixing via a double-roller open mill, has high water absorbency, highwater absorption rate, no toxicity, no irritation to workers and excellent comprehensive performance, is applicable to water prevention, water stoppage, leakage stoppage of civil construction engineering such as railways, highways, urban subways, house construction and the like and to the related fields of water pipe joint sealing and the like, and has good market prospects.