Objectives: The aims of this study were to verify actor and partner effects, by examining the effects of family resilience on post-traumatic stress symptoms (PTSS) among Chinese breast cancer patients and their primary family caregivers. Methods: In this cross-sectional study, 104 breast cancer patients (age range 20–75, Mean = 47, Standard Deviation = 10), and their principal caregivers (n = 104), were recruited from a comprehensive cancer center of a public hospital in China. The patients and their caregivers self-reported sociodemographic, family resilience, and PTSS factors. The actor-partner interdependence model were adopted to examine whether the patients and caregivers' perceived family resilience could contribute to their own ("actor effect") and each other's ("partner effect") PTSS. Results: There were significant correlations between patients' and caregivers' shortened Chinese version of Family Resilience Assessment Scale scores (r = 0.58, p < 0.01) and Post-traumatic Stress Disorder Checklist-Civilian Version scores (r = 0.69, p < 0.01). Caregivers' perceived family resilience was negatively related to their PTSS (actor effect), and the patients' PTSS (partner effect). However, the patients' perceived family resilience was not significantly related to their or the caregivers' PTSS. The primary caregivers' perceived family resilience had both actor and partner effects on patient/caregiver PTSS within the first year of breast cancer diagnosis. Conclusions: Family-based interventions should be designed to enhance family resilience to decrease PTSS within families dealing with cancer patients. Supportive care should focus on the primary family caregivers within the first year of breast cancer diagnosis.