Chinese family is a patriarchal power system. How the system influences young mothers' agency in managing family men's smoking is unknown. Applying a gender lens, this ethnographic study explored how mothers of young children in Chinese extended families reacted to men's smoking. The study sample included 29 participants from 22 families. Semi-structured interviews and field observations were transcribed and analysis was conducted using open coding and constant comparison. The findings indicate that young mothers' interventions to reduce family men's home smoking were mediated by gendered relationships between the mothers and the smokers. The mothers could directly confront their husbands' smoking, although they were more conservative about their men's smoking in the presence of other family smokers. They experienced difficulty in directly confronting senior family men's smoking but found ways to skirt patriarchal constraints, either by persuading seniors to stop smoking in subtle ways, or more importantly, by using other non-smoking family members as "mediators" to influence senior men's smoking. While future smoking cessation interventions should support mothers in protecting their children from tobacco smoke, the interventions should also include other family members who are in a better power position, particularly the grandparents of the children, to reduce home smoking.