UML (unified modeling language) has been widely used in software development. Verifying if a UML model meets the required properties has become a key issue. An approach of model checking UML Statecharts is given in this paper. At first, the UML Statecharts is structurally expressed by extended hierarchical automata. Then, the deduction rules of operational semantics are defined. The correctness of operational semantics can be ensured through finding the maximal non-conflict transition set. For the system with infinite runs, the operational semantics can be mapped to a Büchi automaton. Linear temporal logic properties of the system can be verified based on the automata theory of model checking. The method of verifying a complex multi-object system modeled by Statecharts and collaboration diagram is also presented in this paper.