Abstract: The peak strength of over-consolidated clay is not only related to the degree of consolidation，it is also impacted by stress paths． The method based on the unified hardening model ( UH model) and the generalized nonlinear strength criterion was analyzed the peak strength of over-consolidated clay and offered the theory basis for the over-consolidated clay under complex stress paths． By describing the peak strength of over-consolidated clay under the triaxial compression， constant principal stress，and undrainage consolidation stress path，the relationship of their peak strength could get by UH model． Generalized nonlinear strength criterion was used to describe the non-linear degree of the three paths and to determine the expression equation． The comparation with the test results showed that the proposed analysis method was effective．