Objective To construct symptom network in patients during intermittent period of cancer therapy, to identify core symptoms and symptom clusters, thus to provide reference for precise symptom management. Methods A total of 511 cancer patients were selected by using convenience sampling and asked to fill out the Chinese Version of M.D. Anderson Symptom Inventory and the European Organization for Research and Treatment Center-Quality of Life Questionnaire 30. A symptom network was constructed using an R package to identify the centrality indexes. Exploratory factor analysis was used to determine the symptom clusters. Based on the centrality indexes of symptom network and the influence of symptom cluster on the quality of life through hie-rarchical regression analysis, the core symptom cluster was determined. Results The most common symptoms of patients during intermittent period of cancer therapy were disturbed sleep, fatigue and distress, and the most serious symptoms were fatigue, disturbed sleep, and pain. In the symptom network, sadness was a symptom with the highest node strength （rS=1.12）, fatigue was a symptom with the highest closeness （rC=1.08）, and lack of appetite was a symptom with the highest betweenness （rB=1.38）. Three symptom clusters were extracted: psycho-emotional, gastrointestinal and neurological, which could explain 53.805% of the total variance.Hierarchical regression analysis showed that psycho-emotional symptom cluster had strongest influence on quality of life, with an explained variation of 30.5%. Conclusion Fatigue is the core symptom in cancer patients during intermittent period, sadness is the most important symptom, and lack of appetite is a bridge symptom. Psycho-emotional symptom cluster is the core symptom cluster. Medical staff might formulate management interventions based on the core symptoms and symptom cluster, thus to improve the efficiency of symptom management.