Using the sample of Chinese-listed firms which choice integrated audit from 2012 to 2015, based on the integrated audit background to explore the relationship between the audit relationship mismatch and integrated audit fees. This paper finds Big auditors give an integrated audit discount to small customers and small auditors give an integrated audit discount to large-scale customers. Based on the knowledge spillover effect and linkage mechanism of financial statement audit and internal control audit, further test shows that the auditors who perform the integrated audit can effectively identify the earnings management behavior of listed companies.