This paper aims to investigate the impact of independent directors with industrial expertise on the association between audit complexity and audit fee. About 50 per cent of China’s listed companies hire industry experts as independent directors. We find that the association between audit complexity and audit fee is stronger in firms that have independent directors with industrial expertise than in firms that do not. Furthermore, the impact of independent directors with industrial expertise is more pronounced for firms audited by the Big Four audit firms. The results suggest that the existence of independent directors with industrial expertise stimulates auditors’ awareness of the business risk of their clients, which may help auditors detect clients’ opportunistic behaviour in a complex business environment.