Abstract: Under the auspices of the State Bureau of Seismology a seismic zoning map of China (scale 1:3,000,000) has been compiled and issued in 1977 for the purpose of providing data for anti-seismic constructional designing and basic seismic intensity of various regions of the country.The basic seismic intensity of a region is defined as the maximum intensity to be suffered within a given interval of time in the future under the site condition of that region. The map is a sort of prediction of the basic seismic intensity for the next 100 years after 1973.In this paper, the major principles and methods in composing this map are discussed. Of course, as far as the present state of art of seismic zoning is concerned, the principles and methods used involve many shortcomings and therefore the reliability of the map in predicting seismic intensity is still rather uncertain.