At present,the digital transformation of banks has attracted much attention,but its concept is still inconclusive.This pa-per combs the different levels of digital concept from analog digital transformation to organizational change and strategic transfor-mation,distinguishes the existing concepts of digital transformation according to means theory and purpose theory,explores the heterogeneity of external services and internal management in the digital transformation of domestic and foreign banking indus-try,and determines the digital transformation boundary of China's banking industry that balances both external and internal as-pects.Finally,it gives the understanding that the digital transformation of banks is an endogenous(internal self-driven)"from in-side to outside"digital transformation.