Although most domestic securities companies have established information technology systems，the degree of digitization is far lower than that of other industries and the financial systems of developed countries such as Europe and America. The application scenarios of digital technologies represented by artificial intelligence，blockchain，cloud computing and big data in the securities field have been continuously expanded，which has profoundly changed the business development，risk control and compliance supervision of securities companies. This paper establishes a systematic evaluation system for the digital transformation of securities companies for the first time，which is composed of four aspects：digital strategy，digital business，digital ability and digital governance. It calculates and ranks the digital transformation of 137 securities companies in China，which provides a reference and basis for financial regulatory departments，industry organizations，financial institutions and investors，It provides guidance for securities companies to apply digital technology to reshape their business and governance system. With the rapid development of financial technology and the continuous promotion of financial regulatory reform，digital transformation has become a booster to improve the quality of securities services. It is also an effective way to promote the high-quality development of China’s securities industry.