Earthquake insurance has become a topic of major importance in mainland China ever since the 7.9 Wenchuan earthquake in 2008. Site‐condition amplification is one of the essential factors that influences the prediction of strong ground motion and the assessment of damages of buildings and structures. The site effects should hence be included in calculating earthquake damage and determining the insurance rate for insurance companies. In particular, large‐scale site classification is required for the implementation of earthquake insurance. This study first used a slope method for site classification in China through the values from the topographic slope data and the correlation between and the topographic slope. A novel site classification method, called the slope–geological method, was then proposed in this study to improve the slope method by combining geological characteristics, including geological age, the depositional environment, and soil properties. Four hundred and fifty three pieces of borehole data in Northern Plain and Sichuan of China were used to verify the effectiveness and difference of the slope method and the slope–geological method proposed in this study. Site‐condition classification maps of China were drawn using the slope method and slope–geological method, respectively.