Abstract: The S13 Cr110 steel tubing of Keshen high pressure gas well 2-2-12 cracked and leaked.The causes of tubing cracking and leakage were analyzed by means of macro inspection,magnetic particle inspection and metallographic examination.The results show that the location of cracking and leakage was in the section with weak mechanical property of tubing.The cracking of tubing belonged to stress corrosion cracking.The cause of the crack was related to the corrosion environment of annulus A,the material characteristics and the stress conditions of tubing.The load that caused the cracking and leakage of tubing was mainly related to the bending load caused by the internal pressure and the alternation of thermal expansion and cold contraction.