Offset press can be divided into sheet fed offset press and web offset press according to different paper feeding methods; According to the number of printing colors completed by one feeding, it can be divided into monochrome, two-color, four-color and multi-color printing presses; According to the maximum paper size of the substrate, it can be divided into small offset printing machine, six open, four open, half open and full sheet paper printing machine. In addition, there is a double-sided printing machine that can simultaneously complete printing on both sides with one paper feeding.