Abstract: The high mortality of tumor is one of the most urgent problems to be solved. However, the current clinical trials provide limited quantitative descriptions on dynamic changes of drug efficacy, which restrict the selection of dosing regimens. Quantitative systems pharmacology (QSP) is a new approach for precise treatment of tumors. It quantifies the network relationship between drug action and diseases by integrating the tumor growth and molecules, cells in vivo, thereby predicting the efficacy, toxicity, and mechanism of antitumor drugs as well as identifying predictive biomarkers. In this review, we provide an overview of definition of QSP, current approaches and typical applications in research of antitumor drugs to enhance our understanding of QSP.