Taking M&A events from 2014 to 2016 as the research sample, this paper finds that excess goodwill is significantly positively correlated with the total amount of goodwill impairment within three years from the time of M&A. When an accounting firm, as an intermediary of M&A, has the industry expertise of the industry in which the underlying asset is located, it can inhibit the relationship between excess goodwill and goodwill impairment in the short term. The further study finds that in non-cross-industry M&A and related M&A, the inhibitory effect of auditor industry expertise is more significant. This paper has enriched the research on goodwill and M&A intermediaries, providing empirical evidence for the acquirer to understand the economic consequences of excess goodwill and the employment value of accounting firms.