Abstract: The types of the 3-roll sizing（reducing）pipe mills are summarized according their roll stand profiles，drive types，and structures.The internal correlation between the roll nominal diameter and the roll stand space is described，and two roll groove processing methods are elaborated.Also briefed are three methods for redial adjustment of the roll.Focused on are both the advantages and disadvantages of different main drive types.Named are the specific pipe rolling plants to which different 3-roll sizing（reducing）mills are actually applied.Finally an idea concerning possibility for improving product wall thickness accuracy is put forward.