Abstract: The bridge length and central angle are taken as the parameters to build 30 two-span curved box-girder bridge models.The explicit experimental formulas between the normal stresses of corner points in control sections under different loads and the two parameters is fitted with the nonlinear function method.The sign relationship between variables is used to show the variation trends and degrees of normal stresses influenced by those parameters,and the rules of the normal stresses changing with the parameters under different loads are qualitatively and quantitatively discussed.Advices are finally provided for engineering design.