Abstract: In the practieal project of the Xiedipo tunnel of Yishui Yibin-Shuifu Expressway highway,the stability of double-arch tunnel was analyzed and calculated by the regression analysis and fuzzy probability.The displacement convergence curves of surrounding rock were firstly divided into two types(single-step displacement convergence curve and double-step diplacement convergence curve),which had been regressed by use of the hyperbola function and Boltzman function respectively.Furthermore,the stability of tunnel was calculated with the formula of fuzzy probability.The present formula and experience could be referenced in the design,construction and researches of similar tunnels.