There are some errors in conforming wellhead relative position in multirope friction hoistingsystem according to calculation formula provided by current relative design notebook.Especially,thecalculation error of upsending rope angle and downsending rope angle will affect the calculationprecision of friction wheel surrounding nourish angle.All above will affect the anti slippage calculation of hoisting system.In addition,the other parameters of wellhead such as chord length and arclength are relative with some parameters like static tension during the calculation for hoisting system.Aiming the problems above,the accurate formula to calculation for wellhead relative position in multirope friction hoisting system is proposed.The calculation formulation for surrounding nourish angle isderived by according to the theory of plane analytic geometry and the calculation precision is improved.