With the rapid development of smart grid technology, the accurate management and maintenance of power grid equipment become crucial. Digital twin modeling, as an advanced digital technology, enables real-time monitoring and intelligent decision-making of grid equipment. However, existing technologies face challenges in automatically converting engineering design drawings into digital twin models. In this paper, we propose an automatic identification method for substation equipment based on engineering design drawings, aiming to realize the accurate identification of substation equipment and its coordinates through efficient algorithms, and to provide support for the construction of three-dimensional models and whole life cycle management of power grid equipment. The main contributions of this study include (1) the development of a recognition method for automatically extracting equipment information from CAD drawings; (2) the construction of a spatial index tree R-tree by innovatively combining multilevel indexing and index-comparison binary tree techniques, which significantly improves the efficiency and accuracy of equipment recognition; (3) the realization of an automated equipment matching and searching process, which reduces the manual interventions and lowers the modeling cost; (4) the effectiveness and practicality of the proposed method in real grid equipment modeling is demonstrated through system implementation and validation.