To examine the multidimensional properties of caregiver burden among family caregivers of patients with advanced cancer in a palliative context. A sequential, explanatory, mixed-method study was performed. Family caregivers of patients diagnosed with advanced cancer were recruited from a palliative care department of a third-level hospital in Sichuan Province, China. The Caregiver Burden Inventory, Social Support Rating Scale and Connor-Davidson Resilience Scale were used to collect quantitative data, and a total of 150 caregivers were recruited from January 2022 to September 2022. Qualitative data were collected through semi-structured interviews, and a total of 22 caregivers were interviewed from October 2022 to November 2022. Survey data were analysed using descriptive statistics, and the factors of caregiver burden were identified using the Mann-Whitney U test, Kruskal-Wallis H test and Spearman correlations. Interpretative phenomenological analysis was performed to analyse the interview data to initially explore the multidimensions of caregiver burden. The following-a-thread method and convergence coding matrix were used for triangulation to examine the multidimensional properties of caregiver burden. The participants experienced a moderate level of caregiver burden (32.97 ± 13.09). Through triangulation, six meta-themes and nine meta-subthemes were identified as multidimensional properties of caregiver burden, including physical (too many caring tasks and poor health condition), emotional (strong negative emotions resulting from patients' suffering and insufficient and ineffective family communication), social (less social interaction and social role conflict) and economic burdens, factors that aggravate burden (prevention and control of COVID-19 and spousal relationship with patients) and factors that mitigate burden (social support). Multiple dimensions of caregiver burden were experienced by family caregivers of patients with advanced cancer in the palliative context. Family-centred palliative care must be further developed. It is important to develop family-centred palliative care. Therefore, the focus must be on developing a rational understanding of palliative care in public and a culture-oriented death education in palliative units. This study adopted a mixed-method approach to comprehensively understand the phenomenon of and factors in caregiver burden in the Chinese palliative oncology context. Our findings suggest that family caregivers in palliative oncology experience a moderate level of caregiver burden, with dimensions including physical, emotional, social and economic burdens, among which emotional burden is the most prominent. The findings of this study provide policy makers and nurse practitioners with targets to be addressed in family-centred care in Chinese palliative units. The results of this study are reported based on the guidelines of the Mixed-Methods Article Reporting Standards. Eligible caregivers were invited to participate in the study and semi-structured interviews. Nurse managers of the palliative unit helped us access the patient-management system.