Abstract: A method is presented for use in establishing probability model of seismic intensity attenuation in regions with abundant data of isoseismal maps. Uncertainties which exist both in post-earthquake the evaluation of seismic intensity and in the prediction of intencity of future earthquakes are reflected in the probability model. Probability models for the eastern and the western regions of China have been set up according to the available isoseismal maps of damaging earthquakes in the respective regions. Based on the probability models, instead of the common empirical attenuation formula, a new idea for seismic hazard evaluation has been developed in order to remove some disadvantages inherent in the present hazard evaluations; and the key points for implementing this idea are discussed.