Abstract: Fracture failure happened to the throttling valve sleeve of one single well in a foreign gas field after about 10 days production. The macro morphology, chemical compositions, microstructure, hardness, fracture morphology and so on were analyzed in order to study the failure reasons of the valve sleeve. The results show that:the fracture section of the valve sleeve had a brittle rupture surface with intergranular fracture, and the fracture associated with hoop stress and axial stress; cracks germinated from bottom of the pitting on the outer surface of the valve sleeve, and extended along the wall thickness direction; the stress corrosion cracking occurred to the valve sleeve when it subjected to the large hoop stress.