The invention discloses a guide plate type part wire-electrode cutting fixture and method. Firstly, a first fixture assembly A (1) is installed on a wire-electrode cutting machine tool and fixed; next, the inner surface of a part (6) to be machined is attached to a first positioning face and a second positioning face of the first fixture assembly A (1) and a front end face of a second fixture assembly B (2); then, a positioning dowel (5) is inserted into the part, a second positioning hole of the second fixture assembly B (2) and a first positioning hole of the first fixture assembly A (1); and two pressing plates (3) are pressed to the part (6), clamping to the part (6) is achieved, meanwhile, a plurality of auxiliary supporting points (7) are added to the lower end position of the part (6), and wire-electrode cutting machining of the part (6) is carried out. According to the guide plate type part wire-electrode cutting fixture and method, the structure is simple, operation is convenient, and rapidness, high efficiency, stability and reliability are achieved.