Using a sample of non-financial firms listed in Shanghai and Shenzhen A-shares from 2014-2021, this paper examines the impact of board informal hierarchy on environmental investment and explores the moderating effect of media attention on the relationship between the two. The regression results show that board informal hierarchy is significantly and positively related to firms' environmental investment, and the relationship between board informal hierarchy and firms' environmental investment will be facilitated when firms receive more media coverage.