Abstract: Aiming at acquiring new knowledge, a method is proposed. It takes advantage of the ID3 algorithm of fuzzy decision tree to analyze and process comprehensively numerous multi-source information data in test space, develops an accurate evaluation model and extracts its implied rules. The method has been applied to the examination system of a numerical simulation system in Fengman Hydropower Station, Jilin. Experimental results indicate that such a method for knowledge extraction represents the information fusion idea solving the question of multi-source data, and the high efficiency in processing numerous disorderly and uncertain data.