The utility model discloses an initiating device of a shield machine, which comprises a base and case beam supporting legs. The base is formed by combining a plurality of steel sections longitudinally and transversally in a connected manner and is integrally in the shape of a planar rectangle, the box beam supporting legs are arranged on two sides of the upper side of the base, guide rails are respectively connected onto the box beam supporting legs, and the included angle between two supporting forces acting on the shield machine by the guide rails after the guide rails match with the shield machine ranges from 30 degrees to 90 degrees. The initiating device realizes convenience in placing the shield machine by the aid of the base consisting of the steel sections, a box beam support and the guide rails, the guide rails have guiding functions on the direction of the shield machine, guarantee centering of the shield machine and support a steel section structure in a centering manner, and accordingly the initiating device meets the bearing requirement of the shield machine. The initiating device is widely applied to initiation operation of shield machines.