In order to find out the influence of the interference effect caused by the difference of corrosion pit size on the stress around the pit and predict the corrosion fatigue life. Analyze and calculate the stress distribution and fatigue life of corrosion pit with different center distance and depth under internal pressure load based on ANSYS. The results show that the maximum stress increases with the pit depth, but the number of fatigue cycles decreases. The maximum stress increases greatly when the pits depth and the wall thickness more than 1/3. The interference effect significant when the two pits are tangent and the pit depth is more than 4mm, the stress concentration is more serious and the number of fatigue cycles is sharply reduced. When the two adjacent pits do not intersect the interference effect is not obvious. The stress distribution and fatigue cycle times of two pits adjacent are similar to those of single pit that is there is almost no influence between the two pits.