We propose a computer-assisted cancellation test system (CACTS) to understand the visual attention performance and visual search strategies in school children. The main aim of this paper is to present our design and development of the CACTS and demonstrate some ways in which computer techniques can allow the educator not only to obtain more detailed information of visual search strategies but also to identify the problems of visual attention in school children. We have built a system that utilizes a graphic tablet connected to a PC to monitor the trace of visual search paths as well as the accuracy of visual search responses in school children during the test administration. The preliminary results show that there were no significant difference in correctness between sex, test layouts, and search patterns, except for the performance on different test forms (symbol vs. Chinese radical). The related factors that affect visual search behavior are also discussed.