The contact stress and deformation caused by the flank interference fit of Involute spline pair will affect the accuracy and service life of the parts themselves. In order to determine the reasonable interference amount， the geometric principle for the tooth flank interference of spline is studied， the calculation formulas of radial displacement and circumferential displacement of the tooth flank interference are deduced， and the accuracy of geometric principle is verified by finite element simulation. According to the geometric principle of tooth flank interference， the circumferential stress-strain caused by the hub spline interference values of 0.002 0， 0.002 2 and 0.002?8 mm are tested， the deviations between the finite element simulation results and the test results are 4.9%， 7.6% and 7.1% respectively， indicating that the theoretical analysis conforms to the actual situation， the calculation method proposed in this paper provides theoretical basis for the design of tooth flank interference parameters of Involute spline pair.