Shanghai is an international metropolis. The determination of reasonable ascismic standard has a vital significance to a city for earthquake disaster prevention and reduction

economic construction and so cial sustainable development. The seismic ground motion attenuation relationship is an important content in seismic zonation and seismic safety evaluation of engineering sites for key projects.In existing earthquake intensity attenuation relationship in Shanghai and its vicinity

the statistic results based generally on isoseisms which include historical earthquake data. Because the epicenters of his torical earthquake are not precise

in principle

the historical earthquake data are not suitable to seismic intensity attenuation relationship. In borrowing methods

actual distance is used generally as distance pa rameter in seismic ground motion attenuation relationship

which has different meaning from isoseismic distance. Based on above reasons

in this paper

only earthquakes with modern instrument magnitudes are selected

and the distance parameter of isoseisms is revised. The seismic intensity attenuation lawin Shanghai and its vicinity is established by the union attenuation statistical method.Differences between this paper and the former similar work are : （1）Only the earthquakes with modern instrument magnitudes have been selected to make statistic result comparatively reliable; （2）The revised parameter has been adopted so as to maintain definition of distance parameter of seismic ground motion consistent with intensity attenuation relationship as far as possible.