Abstract: In view of the frequent rod parting problems of screw purnp,this paper analyses the torque transmission characteristics of rod applying elastic mechanics theory,and then presents a rod string design method for torque transmission. This new method gives consideration to the effect of energy storage caused by elastic stress of rod string on increasing rod torque when lower rod cracked field applications. This paper introduces its application by field practical examples. Application results show that the maximum relative error between measured torque and calculated torque is lower than 9%.