A system and method for calibrating oscillograph channels assigns the same value to a drawing parameter of each channel. Each channel receives a signal sent by a signal generator. The oscillograph calculates a voltage difference between a standard signal voltage of a standard channel defined by a user and a signal voltage of each of the other channels. A sequence relationship between each of the other channels and the standard channel is determined. The oscillograph adjusts a deskew value of each of the other channels until each voltage difference is in an allowable range according to the sequence relationship.