In order to analyze the effects of soil structure on the abnormal intensity at Hanyuan old town, based on scientific investigation on seismic damage distribution there, five boreholes were drilled on the frontal landslide slope of the Beihou Mountains and the data of soil layer structures were obtained. The analysis result shows that the soil structure of Hanyuan old town region amplified ground motion, hence leading to abnormal ground motion. This is one of the main reasons for abnormal intensity.