A method for operating a drive train, having a main and, an auxiliary drive and a speed modulation gearbox with a fixed mechanical transmission ratio between the two drives, for starting and towing a drive train to a defined set rotational speed. The main drive is started via a direct-on-line-start with direct coupling to a supply network. The auxiliary drive is started simultaneously with at a time before or at a time after the main drive. For towing the drive train to the defined set rotational speed, which corresponds to a defined percentage of a rated rotational speed of the drive train, the main drive is operated motorically in forward mode at least at times and accelerated to its rated rotational speed, wherein parallel to this the auxiliary drive is operated motorically in reverse mode at least at times.