Data sharing and integration are the inherent request of GIS. Data format conversion, data interoperability and direct data access are three ways of data sharing. All of them have many shortcomings respectively. So this paper proposed a method to build a WebGIS for sharing and integration of multi-source heterogeneous spatial data well. It introduced different data of multi-formats and several spatial database engines into a data access layer which established a unified data structure for screening the difference of different spatial data, and distributed spatial data using the GML, WMS and WFS standards developed by the OGC. Through those ways, it made heterogeneous spatial data homogeneous and enabled different data to have the unified and transparent structure to all users. The results show that the system share and integrate multi-source heterogeneous spatial effectively.