Fatigue and pitting corrosion are two important design considerations for strength assessment of steel structures of the offshore oil and gas industry. In this paper, SIFs along surface crack front calculated are validated by the previous work. Secondly, a numerical approach is developed to computing the crack shape evolution in semielliptical surface cracks in corroded T-joints. Finally, fatigue life of this joint where pitting corrosion is located in direction of the crack face is examined. A series of three-dimensional circular cone pit models together with a semi-elliptical surface crack in a tubular T-joint are simulated in ANSYS. SIFs along surface crack front calculated are validated by the previous work. To validate the model, the results of an un-corroded model are examined against the available results in the literature, and good agreements are observed. According to the numerical results, pitting corrosion in direction of crack face on chord leads to reducing fatigue life of T-joint when decreasing SIF along crack front.