Chemotherapy dose intensity is a momentous parameter of antitumor clinical medication. In certain clinical trials, the actual application dose of the chemotherapeutic drugs is frequently different from the prescribed dose. The chemotherapy dose intensity completed in different trials is also variable, which has an impact on the treatment efficacy, disease prognosis and patient safety. When these agents are tested in the population, chemotherapy reduction and delay or failure to complete the planned cycle constantly occur due to age, performance status, adverse reactions and other reasons, resulting in the modification of the chemotherapy dose intensity. The present review analyzed the correlation between the chemotherapy dose intensity and the incidence of adverse reactions, the treatment efficacy and disease prognosis in clinical trials of metastatic colorectal cancer. Moreover, the clinical applications of chemotherapy dose intensity were discussed. Based on individual differences, the present review analyzed the clinical trials that examined the efficacy of the chemotherapy dose intensity in different patient populations. The conclusions suggested that different populations require a specific dose intensity to reduce treatment toxicity without affecting the curative effect. Contents 1. Introduction 2. Three-drug combination chemotherapy regimens 3. Two-drug combination chemotherapy regimens 4. DI of specific populations 5. Conclusion