Abstract: The elastic constants of rock in compression and tension are different. Considering the difference of modulus including lining and surrounding rock, new solutions of stress and displacement of pressure tunnel were derived based on the bi-modulus theory, and a new expression of elastic resistance was obtained. Based on the theoretical solution, the influence of modulus difference on the mechanical behavior of pressure tunnel was analyzed in detail. The results show that the new solution can be degenerated into the classical solution. The radial stress from the new solution is always larger than that form the classical solution, while the tangential stress from the new solution is smaller than that from the classical solution. The tunnel displacement from the new solution is larger than that from the classical solution. The elastic resistance coefficient of surrounding rock changes parabolically with the increase of modulus ratio between compression and tension. The modulus difference of lining and surrounding rock affects the stress and displacement of pressure tunnel. If the classical solution is used in engineering design, it will inevitably lead to a certain error.