In recent years, immune-targeted drugs represented by PD-1/PD-1L have made unprecedented achievements in the field of tumor treatment. Immunotherapy has become one of the main therapeutic choices for cancer, and consequently, the research and development of immunotherapy drugs has experienced an explosive increase. According to the specific immune targets, the currently developing immunotherapy drugs can be categorized into five types: T cell-targeted therapy, non-specific immunotherapy drugs, adoptive cell therapy, cancer vaccines, and oncolytic viruses. Reviewing various immunotherapy targets, mechanisms of drug action, research frontiers and existing problems can provide guidance and assistance to clinical oncologists and drug researchers. Currently, many immunotherapy drugs have entered the stage of clinical trials and have produced curative effects on different types of tumors. The immunotherapy drugs are expected to bring long-term survival benefits for patients and improve the current dilemmas in treating cancer. At the same time, it should be recognized that there are still many challenges, and that developing immunotherapy drugs needs to be guided by science and rationality.