Abstract: Using appropriate tightening torque to control screw assembly pre-tightening force is an important assembly technology, it is also a difficult point in mechanical assembly. Some researches on torque control have been carried out in our nation, but most of tightening torque standards just list the numerical torque values according to screw strength levels, the degree of torque control is not considered from the perspectives of application objects and connected parts. In this paper, the objects needing torque control in radar assembly procedure are listed, the basic theory of torque control engineering application and the determination principle of torque value are discussed.