In practice, cracks of any awkward shape initiated accidentally, e.g. fabrication errors, exist in structures such as offshore steel structure. Existing of these flaws could lead to disastrous accidence due to fatigue effect. Therefore, a safe interval of maintenances is substantial in order to keep a reliable residual life and strength of the structure. To assess the fatigue effect, one approach is to make use of the stress intensity factor(SIF) of the cracks in facture mechanics. These flaws are usually treated as semi-elliptical surface cracks(with a and c as the minor and major axis) on the member of the structure e.g. BS7910. For plates with semi-elliptical surface crack, Newman, Raju and Kou have reported the stress intensity factor. However, for plates with partly through-wall cracks, namely an semi-elliptical crack with an imaginary crack depth a which is greater than the thickness (T) of the plate, the stress intensity factor was not reported. In the current work, semi-elliptical partly through-wall cracks (of sizes 1.00.2) on a finite plate subjected to remote tension were analysed based on linear elastic fracture mechanics. This work finally produced a comprehensive equation of SIF as a function of a/t and a/2c which was obtained by doing a curve fitting on the SIF which is determined in this work and was obtained by some previous workers.