The invention discloses a method for realizing 3D graphics processing by inputting 2D graphics in a numerically-controlled machine tool system. The method is characterized in that a user inputs a plane figure, then the numerically-controlled machine tool system performs processing on a curved surface according to the plane figure input by the user. The method comprises the following steps: inputting parameters, scattering graphics to be input into primitives, determining center of the graphics input by the user, projecting the graphics input by the user to the curved surface to be processed, and converting coordinates of curved surface to be processed into mechanical axis coordinates. The method provides great convenience for the user to input. The user only provides a work piece to be processed and the plane graphics to be processed on the work piece to be processed without drawing out specific processed graphics.