The incidence of malnutrition in tumor patients is high. As a first-line treatment nutritional therapy is very necessary for tumor patients which should be run through the whole treatment cycle. Oral nutritional supplements as one of the important means of enteral nutrition in artificial nutrition is widely used in clinical practice with still many details of clinical use unclear. Based on the 2018 and later-on ESPEN ASPEN and CSPEN nutrition guidelines this paper searches the pubmed CAJD and Wanfang data from January 1st 2017 to October 31st 2022 for randomized controlled clinical trials expert consensus Meta - analysis and systematic. The search free words are " oral nutrition supplement" " nutrition treatment" " nutrition intervention" " enteral nutrition treatment" and "formula food for special medical purposes". The authors carried out literature reading according to the search results and expanded the search to the references. This paper updated the detailed evidence reporting patients with different tumor pathological types who can benefit from the use of ONS especially the method the dosage of ONS as well as the appropriate formula for different tumor and additional immune enhancing nutrients. The authors used GRADE method to evaluate the evidence so as to provide a theoretical basis for further clinical practice for oral nutritional supplements.