Abstract Background Atrial fibrillation (AF) has been found to decrease quality of life (QOL), and a few studies suggest that family members of AF patients can also experience negative emotions. This study aims to assess the anxiety and depression of the immediate family members of AF patients and to investigate the influence of the QOL of the AF patients on this anxiety and depression. Method This cross-sectional study recruited 121 pairs of AF patients and their immediate relatives along with 121 controls who and whose immediate relatives did not have AF. The patients filled out the Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire, and the relatives and the controls were required to complete the State-Trait Anxiety Inventory (ST-AI) and Self-Rating Depression Scale (SDS). Results The score (mean (SD)) of the State Anxiety Inventory (S-AI, a subscale of ST-AI) in the relatives’ group was 44.9 (10.6), which was significantly higher than that of the control group (38.5 (9.5), p < 0.001). Among the different kinship subgroups, the children of the AF patients had the highest state anxiety score (mean value = 47.0, p=0.075). A negative linear relationship between the patients' overall AFEQT score and the relatives' S-AI score was found (standardized regression coefficient = -0.244, p < 0.001). For those patients who had particularly low AFEQT scores of less than 40, their relatives’ S-AI scores were significantly higher than other members of the relatives’ group (52.1 vs. 42.9, p = 0.001). AF patients in the peri-ablation period (81, 66.9%) had no difference in their AFEQT scores compared to other patients (60.8 vs. 64.4, p= 0.316) and there was also no difference in their family members’ ST-AI or SDS scores. Conclusion Study members showed considerable state anxiety if their family members had AF and increases in this anxiety were positively correlated with decreases in the HRQOL of the AF patients.