The stress intensity factor of a center embedded elliptical crack in non-uniform stress fields, which is along the thickness direction of the plate, is gained based on the linear line-spring model for embedded cracks. The two dimensional weight function is used to transform the non-uniform stress field to an equivalent uniform one. The singular integral equations are formulated and the numerical results in four cases of stress distributions are gained by Gauss-Chebyshev method. The results are in good accordance with those given in the previous literature when a0/c0＜0.4、a0/h≤0.3, and the rationality and reliability of this method are demonstrated.