Focusing on Chinese A-stock companies between 2007 and 2018, this paper examines the impact of client-auditor mismatching on corporate goodwill and the underlying mechanisms. The empirical results show that the client-auditor upward mismatches produce a negative effect on corporate goodwill, while the client-auditor downward mismatches improve corporate goodwill. The above effects are weaker for firms with higher accounting conservatism and marketization degree, which supports the importance of internal governance and external monitoring. These results are robust to considering endogeneity issues, tests on alternative measures of key variables, and subsamples. We further find that client-auditor upward mismatches reduce the impairment of corporate goodwill, but client-auditor downward mismatches have no significant effect on goodwill impairment.