Topological relationships are important spatial relationships, and used in numerous practical applications that involve spatial query and spatial analysis. So it is essential to use formal methods to identify and define a complete and mutually exclusive topological relationship set that can be embedded in spatial query languages. Now, the topological relationships that have been defined cannot represent the topological relationships between the two complex spatial features arbitrarily composed of points, lines and/or polygons, thus the researches on topological relationships are not complete. We introduce the formal definition of mixed geometry, and define a topological relationship set: ｛disjoint, touches, within, crosses, overlaps, contains, equal｝.The set, extending the definitions of topological relationships in ‘OpenGIS Simple Features Specification for SQL’， is complete and exclusive, and can be taken as a unified framework to define topological relationships in spatial query languages.