Oncolytic viruses (OVs) are a type of natural or engineered viruses that preferentially target cancer cells. The engineered OVs can not only target cancer cells, but also regulate the tumor microenvironment which will have some effect on the therapeutic efficacy consequently. Oncolytic viruses are emerging as a system therapeutic strategies by modulating the expression of tumor antigens, immunosuppressive state, tumor-associated fibroblasts and angiogenesis in the tumor microenvironment. Moreover, the combination of OVs and immune checkpoint inhibitor can achieve very good synergistic and complementary effects. This paper summarized the progress of OVs on tumor microenvironment and combination therapy with immune checkpoint inhibitor.