The invention discloses a red mud water permeable brick and a preparation method thereof, relates to the technical field of red mud water permeable bricks, and aims to improve the durability of red mud water permeable bricks. The preparation method comprises following steps: granulating red mud powder to prepare red mud particles; adhering glass powder to the outer surface of red mud particles toform red mud glass cores; mixing the red mud glass cores with a pore forming agent, and carrying out moulding and sintering to prepare the red mud water permeable brick. The body of the water permeable brick is prepared from red mud glass cores; the red mud glass cores comprise red mud particles and glass layers that are wrapped on the outer surfaces of red mud particles; the glass layers efficiently wrap the red mud particles to prevent re-alkalization; moreover, because the strength of glass layers is far higher than the strength of red mud particles, the high pressure resistant performanceof the water permeable brick is strengthened, the test results show that the compression strength of the water permeable brick can reach 42 MPa, and compared with the prior art, the durability is improved.