Abstract: Objective: To clarify the dyadic coping status among young and middle-aged coronary heart disease patients following percutaneous coronary intervention (PCI), analyze its influencing factors, explore its underlying mechanisms, and provide evidence for developing spousal collaborative nursing intervention programs. Methods: Using convenience sampling, 179 young and middle-aged patients with coronary heart disease who underwent PCI at the Cardiology Center of a Grade A tertiary hospital in Guangxi from March to August 2025 were enrolled. Questionnaire surveys were conducted using a general information form, the dyadic coping inventory (DCI), the marriage perception scale (MPS), and the general self-efficacy scale (DSES). Results: The mean total score for DCI among young and middle-aged CHD patients after PCI was 123.10±25.92, that of MPS was 59.38±15.17, and that of GSES was 25.20±6.02. Marital quality and self-efficacy were the independent influencing factors of binary coping levels in young and middle-aged CHD patients after PCI (adjusted R²=0.509, P＜0.001). Marital quality partially mediated the relationship between self-efficacy and dyadic coping in these patients, accounting for 44.35% of the total effect. Conclusion: Dyadic coping among young and middle-aged CHD patients after PCI is at a moderate level, primarily influenced by marital quality and self-efficacy. Self-efficacy directly affects dyadic coping and indirectly influences it by improving marital quality.