The purpose of this study is to develop a computer-based Chinese handwriting assessing system. This on-line evaluation system consist two kinds of input modules, one is copying Chinese characters and the other is memory writing. This system can provide immediate information about students' handwriting process and products. The parameters of process record the spatial and temporal characteristics of handwriting, which including the total time of writing, on paper time, in air time, the ratio of in-air time/ on-paper time, and the speed. The parameter of production is accuracy of handwriting. 25 children aged between 8 and 10 years with dysgraphia and 50 typically developing children of similar age participated in this study. The results indicated that children with dysgraphia had significantly lower accuracy rate in both copy and memory writing tasks. Children with dysgraphia also demonstrated grater the ratio of in-air time/ on-paper time in both copy and memory writing complex characters. The system proposed in this study is able to record the real time handwriting performance of pupil with and without writing difficulties. The kinematic and kinetic indicators provide more information about how children control their motion when writing. Further studies can include more writing forms, such as copying, writing in memory, dictation, and free writing in the assessment system to comprehensively understand the writing problems of the children with dysgraphia.