Abstract: In this article, based on the specific contents of site category of new seismic design code of building (GBT11-39), the practical evaluation method in consideration of fuzzyness between site category and evaluating index has been provided,and the principle of site classification and category index of new code have been described and discussed. The corresponSdin subordinate function was established and the fuzzy vector of site was solved by applying the comprehensiveju dgement theory. Sinca the recommended method i alwsays compatible with new code in selecting any specific limit for index, it may be considered as a supplement of identification metheod for site category to the code. The provided method is easy to use. It may be taken as a effective means for site categore evaluation in practical engineering and seismic microzonation for middle or small cities.