Abstract: Tumor microenvironment plays a crucial role in neoplastic evolution process as it may provide functional interactions between neoplastic and non-neoplastic cells involved in tumor invasion，metastasis and angiogenesis，which implies that it can be regarded as a novel target for the antitumor therapy of polysaccharides. This review focuses on the protumor variations existing in tumor microenvironment，such as growth factors，immunosuppressive factors，proteases，glycoproteins，etc.，which may offer possible mechanisms of polysaccharides on the regulation of their corresponding functions.