Whether to use the seawater to compound the slurry, what materials and treatment agent should be applied and the reasonable application of slurry indices are the important factors for bored grouting pile construction in coastal shoal. Through the comparison of several kinds of slurry material and the optimization of the slurry proportion, analysis was made on the feasibility of bentonite slurry compounded with seawater. With the construction case of bored pile in 2nd blast furnace in Caofeidian, the paper briefly introduced the successful application of bentonite seawater slurry and illustrated the construction control method.