The invention discloses a detecting tool and a detecting method for an inner attached detachable type water-stop band. The detecting tool for the inner attached detachable type water-stop band comprises a convex steel piece matched with the shape of the inner attached detachable type water-stop band and a concave steel piece matched with the convex steel piece, wherein two steel pipes are connected on the convex steel piece, the two steel pipes are respectively connected with a water pipe and a pressure meter, and the inner attached detachable type water-stop band is arranged between the concave steel piece and the convex steel piece when detection is conducted. The detecting method of the inner attached detachable type water-stop band uses the detecting tool for the inner attached detachable type water-stop band to conduct the detection. The detecting method for the inner attached detachable type water-stop band comprises the following steps: (A) tightly compressing and sealing, (B) injecting water and increasing pressure, (C) maintaining pressure, and (D) finishing testing. The inner attached detachable type water-stop band detecting tool and the detecting method thereof can detect the product performance of a water-stop band, is simple in structure, convenient to use, can fast detect the strength of overlapping portions of the water-stop band or other portions of the water-stop band and can fast detect whether water sealing loses effectiveness or not, can control and improve the quality of products in the process of production, and improves the product percent of pass.