As a distinct mode of mathematical representation and communication, geometry diagrams are both signs that represent abstract geometric concepts and visual images that offer graphical-spatial properties. Dynamic geometly environment offers a wide range of tools for its users to create and interact with geometry diagrams. In this paper, I propose a framework to characterize geometry diagrams that learners create in DGEs. The framework considers a learner's approach to creating a geometry diagram (i.e., perceptual-based, measurement-based, construction-based, and transformation-based), the driving force that guides the learner's specific actions in a DGE (i.e., tool-driven, and property-driven), and the constraints in the resulting diagram (i.e., drawing, underconstrained, overconstrained, and appropriately constrained). Examples of student work on two geometry construction problems are used to illustrate the use of the framework. These examples show that the proposed framework provides a useful tool to characterize geometry diagrams in DGEs.