LD-20 3-high pipe cold rolling mill is improved developed from the LD8-15II pipe cold rolling mill which is designed by original Xi’an Heavy Industries Institute, based on the produce practice and the load evaluation in our factory, according to the application situation and suggestions of users. Rolling principle of this machine is described briefly as: 3 roller, which is at the angle of 120° with each other on the cross section in rolling direction, roll reciprocally along the sliding tables of 3 working faces those are of certain curve shapes. By doing this, the rolling grooves will be changed and it could finish rolling the pipe billet between the pushing head and the roller. The billet is charged further by the interval turning feed which synchronizes with the reciprocal movement. After all of these finish, a complete rolling course finishes. Finished pipes rolled by this machine are of high precision, nice surface quality and improved mechanical performances. They are fit for being produced into various steel pipes, non-ferrous pipes and alloy pipes with high precision, high strength and thin pipe wall, including briefly 20, 45, 30CrMnSiA, 1Cr18Ni9Ti etc.