We use A-share listed manufacturing companies in China from year 2010 to 2016 as the sample to examine whether the supplier/customer concentration affects the persistence of company's earnings. The results show that the supplier/customer concentration will negatively affect the persistence of earnings. Further studies find that the increase of market competitive power significantly weakens the negative impact of supplier/customer concentration on the persistence of earnings. Compared to private enterprises， state-owned enterprises significantly alleviate the negative impact of supplier/customer concentration on the persistence of earnings. Meanwhile， the increase of institutional ownership inhibits the negative relationship between supplier/customer concentration and the persistence of earnings. Mechanism analysis shows that supplier concentration is negatively associated with the rate of margin and customer concentration is positively associated with operational risk， which leads to the negative influence on persistence of earnings.