Abstract: Liujiagou Formation of Daniudi Gas Field is low fracture pressure belt, so fluctuating pressure caused by casing running may easily lead to fluid leakage. In order to solve this problem, a model for calculating fluctuating pressure when running casing was built based on the steady fluctuating pressure theory, considering the local resistance effect of cenrralizer. Then the effect of drilling fluid properties, casing running speed and annular clearance, etc. on fluctuating pressure were analyzed based on the model. Result shows that, with increase of drilling fluid density and consistency coefficients, gel strength, casing running speed and centralizers, the fluctuating pressure increases with the decrease of annular clearance. In view of the influencing factors of fluctuating pressure, this paper presents the technical countermeasures for safe casing running, which is of great reference significance to avoid leakage of Liujiagou Formation caused by pressure fluctuation during casing running.