Due to the wide application of digital tools and the improvement in interactive technologies, design thinking might change in digital world comparing to that in traditional design process. This study aims to explore the difference of design thinking between three kinds of sketching tools, i.e. hand-sketch, tablet, and pen-input display, by means of conducting 27 sessions of design trials. Totally, nine industrial design students as the participants were recruited to develop the concept sketches. Each participant has to undertake three sessions, and use one of the three kinds of sketching tool in one session for about 40 min. With a retrospective interview survey to all the participants followed by a protocol analysis to the transcriptions of the interview, a coding framework including six visual think behavior codes (i.e. transform, manipulate, concretize, abstract, modify and timescan) and four visual thinking strategy codes (thinking, feeling watching/listening, and other) were developed, and used to analyze the difference of occurrence frequency of the visual thinking behaviors and strategies. Furthermore, a one-way ANOVA and stepwise regression analysis were applied to inspect the correlation of behaviors and strategies of design visual thinking. The results show the different roles of sketching tools in affecting the occurrences frequency of various visual thinking behaviors and strategies, and the correlation between visual thinking strategies and behaviors. The conclusion was made by proposing the approach facilitating the design concept development in design education within digital world as well as the suggestion to future research work.