Of the stability analyses of embankment reinforced by geo-synthetic material, the traditional Sweden slice method obviously owes its conservation to the misunderstanding of reinforcement mechanism of geo-synthetic material. Deep studies of the failure and reinforcement mechanism of geo-synthetic material show that the reinforcement effects of geo-synthetic material were considerably underestimated. Therefore, a new stability analysis method of embankment reinforced by geo-synthetic material, called modification of Sweden slice method, is presented by modifying the assumption of reinforcement effects. The in-situ case demonstrates the presented method is effective and practical.