Abstract: Taking small and medium-sized companies listed in Shenzhen Stock Exchange from 2015 to 2020 as the research sample, the empirical tests on the inner correlation among internal control quality, audit opinion and enterprise commercial credit financing were conducted. The results showed that the internal control quality were positively correlated with commercial credit financing; the quality of internal control could facilitate the audit opinions; and audit opinions played a partial intermediary role in the process of internal control quality promoting commercial credit financing.