Objective To systematically evaluate and synthesize qualitative studies on factors influencing family involvement in ICU patients′ nursing activities, so as to provide evidences for optimizing the ICU care model and formulating intervention programs. Methods We searched databases including CNKI, Wanfang Data, SinoMed, VIP, Cochrane Library, PubMed, Embase, Web of Science and CINAHL from inception to April 2025, to collect qualitative studies exploring the factors affecting family involvement in ICU patients′ nursing activities. The results were synthesized by integrating methods. Results A total of 12 studies were included, with 40 complete research findings grouped into 10 categories by their similarities. Three integrated findings were synthesized:personal factors, interpersonal factors, healthcare system and environmental factors. Conclusion Family involvement in ICU patients′ nursing activities is influenced by multiple factors. It is necessary to comprehensively assess the conditions of both patients and their families, provide information and skill support to the family, enhance staff training, and improve systems and the environment to promote better family involvement in ICU patients′ nursing activities.