Abstract: Based on the theory of spatial analytic geometry,the formula for calculation the gap between the upper disc and left roll of Accu-roll pipe rolling mill is deduced.In addition,relevant calculation and analysis in this regard is made according to a given manufacturer's actual situation of the said pipe mill.Such efforts provide theoretic basis for solution of problems as encountered in operation of the mill,such as inner spiral mark of the shell,low rolling speed and short service life of the disc in case of rolling light-wall tube,and for optimum determination and adjustment of the process parameters concerning the guide disc and roll,etc.