A simple, rapid and efficient approach to constructing 3D conceptual solid models on sketch-based user interface is presented. It emulates the traditional sketching design approach with paper and pencil to sketch strokes on the calligraphic interface, and then applies the feature-based modeling method to construct different sweep feature-based primitives according to the shape and location relationship of feature strokes. In order to construct complex solid models, the feature joining and cutting mechanism based on intention capturing is introduced. This paper illustrates the implementation of the algorithm, and experiment shows that the algorithm is efficient and well suitable for real time on-line 3D conceptual model creation.