Triple negative breast cancer is a subtype of breast cancer with poor prognosis and lack of effective treatment. Cyclin dependent kinase（CDK）4/6 inhibitors promote antitumor immunity by influencing the triple negative breast cancer immune microenvironment, such as increasing the tumor cell surface pragrammed death-ligand 1 protein expression, enhancing T cell activation and antigen presentation, changing the proportion of T cell subgroup and inducing lymphocyte infiltration. The change of immune microenvironment is related to tumor progression, but its mechanism is extremely complex. Exploring the mechanism of CDK4/6 inhibitor affecting immune microenvironment and its biomarkers can provide a new direction for the diagnosis and treatment of triple negative breast cancer.