Abstract: In order to evaluate fatigue of VDT(visual display terminal) operators, an evaluation index system and a two-grade fuzzy synthetic evaluation model of VDT operators' fatigue are set up based on fuzzy mathematics theory and the fatigue characteristic of VDT operators. The case studies show the model is effective in evaluating VDT operators' fatigue. The data to build judgment matrix is obtained by questionnaire, which costs a little but is reliable. The two-grade fuzzy synthetic evaluation model of VDT operators' fatigue can be easily applied in companies to evaluate VDT operators' fatigue.