BackgroundLung cancer is a malignancy of high incidence rate and mortality in China. The fear of relapse can affect the patient's treatment compliance and reduce their quality of life. There have been previous studies on the relationship between fear of lung cancer relapse and disease perception， as well as disease perception and psychological flexibility. However， current research on the status quo of fear of lung cancer relapse and its correlation with illness perception and psychological flexibility is limited. ObjectiveTo explore the fear of cancer relapse and its relations with illness perception and psychological flexibility in patients with lung cancer， and to provide references for subsequent related clinical interventions. MethodsA total of 96 patients were selected as the research subjects， who were pathologically diagnosed with lung cancer and admitted to Fuyang People's Hospital from January 2021 to July 2022. Fear of Progression Questionnaire-Short Form （FoP-Q-SF）， Brief Illness Perception Questionnaire （BIPQ） and Acceptance and Action Questionnaire-Ⅱ （AAQ-Ⅱ） were used for evaluation. Pearson correlation analysis was used to examine the correlation between scores of various scales， and multiple linear regression analysis was used to explore the influencing factors of relapse fear in lung cancer patients. ResultsThe total FoP-Q-SF score of lung cancer patients was （35.35±7.66） and a total of 65 cases （67.71%） had a FoP-Q-SF score≥34. As relevant analyses showed， the BIPQ total score of lung cancer patients was positively correlated with the total score， social family dimension score and physiological health dimension score of Fop-Q-SF （r=0.586， 0.445， 0.475， P<0.05）， the AAQ-Ⅱ score was positively correlated with the total score， social family dimension score and physiological health dimension score of FoP-Q-SF （r=0.485， 0.652， 0.513， P<0.05）. According to the results of single factor analysis and multiple linear regression analysis， age （β=-0.142， P<0.01）， education level （β=-0.254， P<0.01）， monthly household income （β=-0.527， P<0.01）， illness perception （β=0.847， P<0.01） and psychological flexibility （β=0.781， P<0.01） are all factors influencing the fear of relapse in lung cancer patients. ConclusionMost lung cancer patients have a fear of recurrence. It is not only related to illness perception and psychological flexibility， but also influenced by factors including age， education level and monthly family income.［Funded by Special Research Project on Business Construction of National Clinical Research Base of Traditional Chinese Medicine under the State Administration of Traditional Chinese Medicine （number， JDZX2015074）］