Pen-based user interface relying on touch technology is one of the Post-WIMP interfaces. It discards the physical keyboard and mouse, which changed the method of human-computer interaction to some extent. Though sketch drawing software and recognition software are constantly emerging, there is no mature pen-based interface design development tool. Based on the PGIS interaction paradigm and scenario design method, this paper develops a tool named with SDT that allows hybrid input of graphics and sketchs based on pen-based interaction primitives. Firstly, based on the principle of high-cohesion and low-coupling in the field of software engineering, the "Separation-Fusion" design method is proposed. Accordingly, the overall architecture of the system is put forward. Secondly, the essential technologies are elaborated from three aspects:user interface description language, pen-based interactive primitive and mono-case, hybrid input. Thirdly, an example of a complete application is built by the SDT, which makes the availability and feasibility of the system more convincible. Finally, the advantage and effectiveness of the tool are verified by two evaluation experiments.