Abstract: Therapeutic drug monitoring(TDM) is a very important tool in the clinical treatment of antitumor drugs. However, TDM of various small molecule targeted anti-tumor drugs has not been fully applied in clinical practice, and there are still many imperfections in the guidelines for TDM, mainly due to the large interindividual differences in pharmacokinetics/pharmacodynamics of small molecule targeted anti-tumor drugs, the influence of various factors on pharmacokinetic parameters, and difficulties in determining drug concentrations in patients. In addition, different small molecule targeted anti-tumor drugs may differ in monitoring indicators for TDM, and the quantitative analysis methods used are also different. Therefore, individualized therapeutic drug monitoring is beneficial for maximizing the rationality of medication. This review provides an overview of the existing small molecule targeted anti-tumor drug TDM, and briefly summarizes the current research status of orally targeted anti-tumor drug TDM developed domestically, in order to improve the monitoring and treatment plans for targeted anti-tumor drugs and promote their clinical rational use.