An aircraft assembly data integration method based on a virtual central data source was proposed to solve the problem of multi-source heterogeneity in aircraft assembly data, promote data sharing and maximize utilization. The accessibility of data was improved by constructing a virtual central data source on top of the local data sources. The aircraft assembly data were divided into three classes, which were assembly object data, assembly system data, and assembly task data. A global system data model with five layers was proposed to establish a global uniform index rule, which can support data requesters to express data requirements without ambiguity and avoid the problem of semantic heterogeneity. The method was implemented by a software called assembly data integration middleware, which was used to integrate data in the assembly of the outer wing box. The application verification and test of the middleware were carried out. Results show that the data integration middleware can achieve the integration of multi-source heterogeneous aircraft assembly data and improve the accessibility of multi-source heterogeneous data with high concurrency performance.