In recent years, the use of immune checkpoint inhibitors (ICI) for tumor immunotherapy has received widespread attention. The development of checkpoint blocking antibodies against cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1) has brought great hope for the treatment of melanoma and other tumors. There is no evidence that immune checkpoint inhibitors increase the risk of infection, but the upregulation of immune function leads to a series of immune-related adverse events (irAEs) which requires immunosuppressive therapy, and may lead to opportunistic infection. Cases of latent or chronic infection reactivation in the absence of irAEs have been reported. In this review, we focus on the phenomena, possible mechanisms and related prevention and treatment strategies of infectious complications associated with the use of immune checkpoint inhibitors in oncology.