To meet the needs of risk assessment of power transformer in power system, a condition assessment model of power transformer based on fuzzy evaluation method and information fusion technology is proposed in this paper. Typical parameters of preventative test and on-line monitoring are selected to evaluate operational condition of power transformer. The selected condition parameters are normalized at first and then calculated membership to different condition level. A multi-information fusion method based on Dempster-Shafer evidential theory is employed. Moreover, data form routine test and on-line monitoring of a 220kV power transformer is analyzed and the results verified the validity of the proposed model. It is indicated that the proposed method is helpful to improving the accuracy and timeliness of transformer condition evaluation by combining on-line monitoring parameters.