The invention belongs to the field of high-molecular materials and particularly relates to high-fluidity and high-anti-impact ABS resin and a preparation method thereof. The ABS resin includes the following components, by mass, 20.0-40.0 parts of an ABS grafted powder material, 60.0-80.0 parts of high-fluidity SAN resin, 0-2.0 parts of an antioxidant, 0-2.0 parts of a lubricant, 0.0-2.0 parts of a stabilizer and 0.0-2.0 parts of an antistatic agent, wherein the ABS grafted powder material includes the following components, by mass, 40.0-70.0 parts of polydiene latex, 15.0-40.0 parts of styrene, 5.0-30.0 parts of acrylonitrile, 0-2.0 parts of a reducing agent, 0-2.0 parts of an initiator, 0-5.0 parts of an emulsifier, 80.0-200.0 parts of deionized water and 0-1.0 part of a molecular weight regulator. The ABS resin overcomes the defects in products in the prior art, has both high anti-impact strength and fluidity, has excellent processability and dimensional stability, and satisfies the use demand on large-size products processing in the fields of household appliances, automobiles and the like.