Abstract: Handwriting is generally regarded as the most traditional and natural way for composing. However, the non-natural mouse clicking is still employed to input musical notes by most existing composing software mainly due to restricted control in the writing process and difficulty in automatic recognition of handwritten musical notes. In order to solve this problem, a "naturalness-" and "satisfaction-" oriented approach to interactive design is proposed in this paper. The tape-magnifier model and the free-scratch model are introduced to restore the naturalness and fluency of paper-and-pen composing as much as possible, and an approach to handwritten musical notes recognition based on boundary scanning and classification is proposed which can be used to the automatic recognition of several different kinds of musical notes. The experimental results show that the recognition method has strong ability of fault tolerance and the interaction design has high user satisfaction.