A new image segmentation algorithm using level set method was presented，which is based on the gradient vector field flux fitting energy.Combing with the penalizing energy term of signed distance function and minimizing the energy functional，we obtain the variational formulation which has four main advantages over the traditional active contour models.First，the difficulty of segmentation with weak edge can be addressed.Second，the level set function allows for flexible initialization and needs no re-initialization during evolution.Third，the level set function can be easily implemented by simple finite difference scheme and is computationally more efficient.Fourth，the interior contour of object can be automatically detected with only one initial contour.The proposed algorithm has been applied to both synthetic and real images with promising results and the results of segmenting weak edge objects and images with intensity inhomogeneity are better than using either geodesic active contour (CAC) model or C-V active contour model，respectively.