Concept of ecological niche is introduced to analyze the relations of e-commerce and traditional business, the latent ecological niche and actual ecological niche, large sized enterprise and small and medium sized enterprise (SME) in this paper. The e-commerce adoptions in SMEs and their attitudes towards the use of strategies were examined. Then four strategies of e-commerce for SMEs based on Niche Theory was put forward, namely dislocation management strategies, value innovation strategies, resources expansion strategies, and utilization of the third-party e-commerce service platform strategies. Finally we suggest that SMEs within the different niches should frame different strategies to develop the e-commerce in future.