Steel sheet pile is a kind of section steel with lock. Its section has straight plate shape, groove shape and Z shape, etc., and there are various sizes and interlocking forms. The common ones are Larson type, Lackawanna type and so on. Its advantages are: high strength, easy to drive into hard soil layer; it can be constructed in deep water, and if necessary, it can be added with oblique support to form a cage. Good waterproof performance; cofferdams of various shapes can be formed according to needs, and can be reused many times, so it has a wide range of uses.