abstract: We consider the flow of a closed immersed hypersurface evolving along its normal direction with speed Hk, where H is mean curvature and k is a positive constant. It is a natural generalization of the well known mean curvature flow. For convex initial hypersurface, such flow will develop singularities after finite time, which can be classified as two types according to the blow up rate. We study the structure of the rescaled limit, and show that for a Type I singularity, the limiting hypersurface satisfies an elliptic equation. For a Type II singularity, the limiting hypersurface must be a translating soliton.