A control system for a sewing machine, which is operable in a simulation manner as if the control system is connected to the sewing machine. When a sewing-machine control system starts a main control process, a status of its connection to a sewing machine is detected. If the connection is established, a connection flag is set. If it is not established, a connection flag is reset. A display device displays a menu select screen having a list of items, and a desired item is selected from the list. When the selected item is "Sewing process", the sewing-machine control device operates in the following manner. If the sewing-machine control device is not connected to the embroidering sewing machine, a virtual sewing-machine control program is executed to set "in-sewing" data for the pseudo status information, "0" as the initial value for a pseudo number-of-stitches; and "1800" for a pseudo rotation speed signal. The display device displays a pseudo sewing screen, constructed with those items of information.