The structural investigation model was presented based on the circle theory so as to study the influence of different constructions

sizes and positions of secondary sealing ring on torsion deformation of the typical mechanical seal ring.High pressure mechanical seal design theories and methods were discussed. The results showed that the method of analytical calculation instead of the finite element method was feasible and effective.The step on the complex section of sealing ring could be directly ignored when the step size of length or width was smaller than 4 mm.Different constructions and placements of the secondary sealing ring were important factors affecting torsion deformation of mechanical seal ring.A small variation of ring size would not affect torsional deformation.The design theory and method of high pressure mechanical seal were improved.