Abstract：Safety of secondary lining is of utmost importance to tunnel engineering quality as the main bearing structure and the last water-prevent line for rock types I，II，III. In this paper，firstly the rock stress on secondary lining of a freeway tunnel is obtained to provide a comparable criteria for its measured data，according to design specification of highway tunnel and P′s theory. Then the secondary lining strength in maximal measured-stress face is checked on the basis of numerical results of internal stress obtained by using GeoFBA code of Tongji University and design specification of highway tunnel. Finally，the reasons of the induced microcracks are listed after consideration of design parameters，given engineering case，and construction speed.
