Property graph manages data by vertices and edges. Each vertex and edge can have a property map, storing ad hoc attribute and its value. Label can be attached to vertices and edges to group them. While this schema-less methodology is very flexible for data evolvement and for managing explosive graph element, it has two shortcomings-- 1) data dependency 2) less compression. Both problems can be solved by a schema based approach. In this paper, a type system used to model property graph is defined. Based on the type system, the associated data definition language (DDL) is proposed and multiple graph instances created under this type system is discussed.