Coal bed thickness measuring tool and method for coal mine fully-mechanized coal mining face

The invention discloses a coal bed thickness measuring tool for a coal mine fully-mechanized coal mining face. The tool comprises an extension scale, a fixing rotating shaft and two stretchable measuring pins; one ends of the two stretchable measuring pins are hinged through the fixing rotating shaft, the box end of the extension scale is arranged at one stretchable measuring pin, the hook end ofthe extension scale is fixedly connected with the other stretchable measuring pin, a measuring worker can measure the thickness of a coal bed without standing below a coal wall, even when the top plate of the working face is poor in condition, measurement can still be performed by adopting the measuring tool, the measuring result is accurate, operation is safe, the measuring work can be achieved without hanging a working face hydraulic support top beam, and by reading data on the extension scale, on the basis of the principle that the height ratio of similar triangles is equal to the bottom edge ratio, the working fac