Natural interaction based on pen gesture is efficient for innovation in conceptual design. This paper presents a hierarchy concept model for pen gesture design based on the interactive informal constraint sketch and context-awareness. Furthermore, it discusses the constraint foundation and solution. Feature gesture as an instance of gesture applications in conceptual design is given. Compared with the traditional modeling mode, the feature gesture is convenient. Gesture-based interaction gives a natural way to record the brain streaming quickly. This paper provides an efficient method for innovative design to improve human-computer interaction.