Drugs will be affected by various factors in the body, with the increasing of human food varieties and the diversity of dietary structure, food has increasingly become a factor that can not be ignored, especially oral drugs. It may occur in the astrointestinal tube firstly by various physical and chemical reactions, and then affect the PK and PD of the drug, leading to changes in drug treatment outcoming. Equally, drugs may also affect the appetite and the absorption and utilization of the food and nutrients, leading to nutrient disorder or imbalance. Now people take more attention on this area. This paper introduces the classification and occurrencing lacation of the interaction between food and drug, some food, especially grapefruit juice and some other fruit juice, affecting the inhibitory pathway of the CYP3A enzyme system on the drug metabolism, and the effect of the drug on the absorption, metabolism and excretion of food, and the common interaction of oral antitumor drugs and food and the cautions for use . Clinical medical staff and pharmacists should understand and master the basic knowledge and common examples of food and drug interactions, educate patients about rational use of drugs, avoiding taking interacting foods, which could reduce the drug induced damage or treatment failure due to improper diet and achieve the optimal treatment effect.