Objective:To explore the change trajectory and influencing factors of benefit finding of family caregivers of patients with lung cancer, so as to provide reference for formulating individualized intervention strategies.Methods:This study was a cross-sectional survey. From September 2021 to October 2022, 232 family caregivers of patients with lung cancer from General Hospital of PLA Central Theater Command and Tianyou Hospital affiliated to Wuhan University of Science and Technology were collected by convenience sampling method. The level of benefit finding of family caregivers was investigated at 1 month, 3 months and 6 month, after the patients were diagnosed. Growth Mixture Model was applied to identify distinct trajectory categories. Multinomial Logistic regressions were performed to analyze predictors of trajectory categories.Results:The overall level of benefit finding of family caregivers of lung cancer patients showed an upward trend over time ( F=83.06, P<0.01), from 1 month (47.02 ± 14.79) to 6 months (58.13 ± 13.18). Three categories of benefit finding trajectories were identified, named as "the high level-decline group" 12 cases, "the moderate level-stability group" 67 cases, and "the low level-elevation group" 153 cases. Univariate analysis showed that age and education level of family caregivers, average income per person in patient family, type of medical payment, whether the tumor was metastasized, the treatment method of the patient, whether they lived with the patient, and whether they had co-caregivers were related to the category of benefit finding trajectory ( χ2 values were 6.71-15.05, all P<0.05). Multivariate Logistic regression analysis showed that age and education level of family caregivers, average income per person in patient family, treatment method of the patient and whether they lived with the patients were the main influencing factors of benefit finding trajectory categories(all P<0.05). Conclusions:The benefit finding of family caregivers of lung cancer patients showed different trajectories with the time of diagnosis, and the overall level shows an upward trend. More than half of the family caregivers belong to the low level-elevation group. Medical staff should give family caregivers stage and specific nursing intervention according to the change trajectory of benefit finding and its influencing factors.