Abstract: To estimate seismic damage of highway beam bridges quickly and accurately,influence factors of the seismic damage were more reasonably reselected in an improved methodology based on Zhu Mei-zhen's empirical methodology.The least squares method was used to analyze the data of partial bridges in Tangshan earthquake and Wenchuan earthquake.The improved methodology was formed with new regression coefficients of the influence factors.The main difference between the improved and original methodologies is that site classification and seismic intensity are considered together to take place of the influence factor of liquefaction and instability of side slope that are taken into account in original methodology.By using both the improved and original methodologies,some highway beam bridges in Wenchuan earthquake were estimated.Results show that compared with the real seismic damages,the improved model is preliminarily validated to be more accurate.