The construction of digital transformation capabilities in traditional manufacturing enterprises is an important measure to promote and implement digital transformation strategies. From the perspective of digital construction of traditional enterprise business process systems, a capability evaluation index system is constructed, which consists of digital infrastructure, digital R&D, digital technology application, digital marketing, and digital talents. Taking Baosteel, an advanced steel enterprise, as an example, this paper evaluates and analyzes the evolution of the company’s digital transformation capabilities from 2012 to 2019. The results show that the evolution of the digital transformation capability of Baosteel presented a fluctuating and rising situation. Through grounded theory analysis, it is revealed that the capability formation mechanisms and their effects during Baosteel’s digital transformation include digital capabilities, digital supporting factors, and external environmental influences. Based on these findings, countermeasures and suggestions for the construction and enhancement of digital transformation capabilities in traditional enterprises are proposed.