In 2016, China made new regulations on audit report. The core change is that key audit matters are added to the audit report. Since then, key audit matters have become a new hotspot in the field of audit research. This paper mainly studies the disclosure status of key audit matters in China and the factors affecting the disclosure. This paper will quantify the characteristics of key audit matters and study its impact on the disclosure of key audit matters from the two levels of firm and auditor. This article uses data from listed companies that have disclosed key audit matters from 2016 to 2018, and uses mean testing and regression research methods to analyze how the characteristics of firms and auditors will affect the disclosure of key audit matters. The study found that: 1) the number of key audit matters, the length of the text, the length and proportion of digital figures, and industry-specific key audit matters fluctuated significantly from 2016 to 2017 and stabilized from 2017 to 2018; 2) The size of the firm, the audit term, the firm’s industry expertise, and the auditor’s gender, years of practice, and industry expertise will significantly affect the disclosure of key audit matters. This article provides evidence that the characteristics of firms and auditors affect the disclosure of key audit matters and expands research on key audit matters.