UML is a semantically rich language, but it is difficult to ensure consistency of the diagrams you have written. Therefore, in this paper, we propose cross checking rules to improve consistency between UML diagrams, especially between UML static diagram and dynamic diagram. We use metamodels in order to more clearly reflect interactions of UML elements in the checking rules and use OCL(Object Constraint Language) to accurately represent the checking rules. By comparing with the well-formedness rules of UML specification, we focus on consistency of UML diagrams. And we derive metamodels of static diagram and dynamic diagram, analysis the relationships of UML diagrams and finally, we test the usability of derived rules through a case study.