Abstract: Fault dip angle is introduced to reflect the impact of surface displacement of strike-slip dip angle based on classic strike-slip displacement formula.Due to the dip angle of the fault, surface projection is the interface between locking and sliding motion on the fault, where deformation varies greatly.The dip term in the formula represents the fitting dip angle, which represents the overall offset of the surface and the locking-sliding boundary on the fault, and its value is often smaller than the near-surface measurement of dip angle.It was applied in the profile analysis of the main strike-slip fault deformation characteristics of the eastern boundary of the Sichuan-Yunnan block before and after the Wenchuan earthquake by using the improved formula as the fitting formula of the fault profile analysis.The fitting results obtained are consistent with those obtained by other methods.The improved formula reflects the deformation of the fault more objectively than the original one.Because the profile analysis for a single fault is affected by many factors, the fitting results have to be further analyzed in actual situations.