The invention relates to an advance pre-grouting construction method for an underwater tunnel in case of a fault zone. As for the advance pre-grouting construction method for the underwater tunnel in case of the fault zone, the structure is simple, construction is convenient, cost is low, and construction safety can be ensured. According to the technical scheme, the construction method has the following steps that a, tunnel face advance geological forecast is carried out on the tunnel face of the underwater tunnel; b, advance drilling and core taking are carried out, and the water drainage structure of the tunnel face of the underwater tunnel and the location of a fault ahead are judged accordingly; c, advance pre-grouting parameters are determined according to the geological conditions, detected in the steps a and b, of surrounding rock in front of the tunnel face of the underwater tunnel; and d, advance drilling construction for advance pre-grouting is carried out through a drilling and grouting integrated machine, grouting for water shutoff is carried out through a conventional grouting device after drilling construction is completed, at this moment, the drilling and grouting integrated machine is moved to the next hole position, and when water is drained and the drainage amount of water is larger than 50L/s in the drilling process of the drilling and grouting integrated machine, the drilling and grouting integrated machine is adopted for grouting to stop water.