Abstract: To solve the problems of rolling along the line of long thick-walled drill collar tubes (the ratio of outer diameter and wall thickness (D/S) ≤ 3. 7) in Assel mill and promote the uniform of wall thickness, a series of technical measures were carried out, such as optimizing the billet properly, distributing the deformation reasonably, adjusting the parameters of piercer and Assel mill, and optimizing the pass parameters and the speed setting of the reducing mill. The length of finished drill collar tubes completely meets the standard, and the uniform of wall thickness in transversal and longitudinal directions reaches the higher standard. The user experience shows that, the use of tubes as raw materials is better than that of bars in saving materials, promoting the pass rate, improving the efficiency, and reducing the tool consumption.