Abstract:The multiple sources and inconsistency of legal event codes in different databases have greatly hindered the classification of patent legal events and the deep processing of data, and a hierarchical and systematic classification architecture has not yet been formed. Therefore, this study takes the global patent legal status XML data provided by the European Patent Office (EPO) as the research object, and introduces the data coverage and data formats of different types of exchange data in detail. Based on the comparison of patent legal status in famous patent retrieval and analysis platforms, such as PatSnap, Innography, IncoPat, SooPAT, WanXiangYun and Baiten, the legal status of EPO patents can be classified into six categories: pending, granted, valid, invalid, technology transfer and others. According to the position of each category in the patent life cycle, the validity of the current legal status of patents is divided into three states: pending, valid and invalid. At the same time, the transfer code and patent license code in more than 4000 EPO legal event codes are classified and indexed in detail. Through the research on the key issues such as the construction of the classification system of patent legal status, the determination of the current validity of patents, and the classification of patent technology transfer, the EPO patent data is structured and deeply processed, so as to build the physical model of the EPO patent legal status database and provide support for improving the quality and efficiency of patent retrieval and analysis.