Abstract: Elaborated in the paper are the development of the three-roll stretch reducing mill, and the commonly- used methods for roll pass design thereof. With the theory of pass design of power function reduction rate-based the stretch reducing mill, and the characteristics of the stretch reducing mill of the Φ168 mm PQF 3-roll mandrel mill plant, a package of roll passes of function reduction rate-based stretch reducing mill suitable for this stretch mill is designed. The pass package neutralizes the influence by the velocity and temperature on the groups of motors and gear boxes of the stretch reducing mill, and particularly, gets the actual loads of the No.2 group of motors and gear boxes remarkably increased.