The formation of intensity attenuation law is essential for traditional probabilistic seismic hazard analysis（PSHA） at a specific site to predict engineering strong ground motion for a given exceeding probabilistic level by earthquake pair mapping method

thus the rational evaluation of statistical factors determining the intensity distribution law is essentially critical to the final PSHA results

and it has economical application.This paper

focusing on the historical earthquake isoseismals in a typical seismic moderate area of Southern Central China（SCC）

gives firstly an introduction of Joyner-Boore（J-B） method of LSE in intensity data fitting

then adopts different attenuation relationships of intensity in SCC over epicentral distances and magnitude of surface wave

including that of equivalent circle vs.radius

that of ellipse

and that of joint ellipse vs.long-axis or short axis.Nonlinear parameter estimation and standard deviation of above models are also tabulated by Joyner-Boore（J-B） method of LSE and ordinary least square estimation（OLSE） in intensity data fitting.Finally

comparisons of these results derived from this paper with those in previous studies in the same area and with that typical in West America are performed.Results show:（1） Different models of intensity attenuation law and intensity data applied are both crucial for statistical analysis of historical isoseismals to predict the mean earthquake intensity at a specific site

and the mean intensity predictions by various models applied in this study is fairly consistent;（2） Intensity predicted at a short distance by Joyner-Boore（J-B） method of LSE is much higher than by OLSE in SCC intensity data fitting

but the difference will dilute even reverse at a longer epicentral distance;（3） Intensity attenuation law by epicentral distances and magnitude of surface wave of joint ellipse vs.long-axis or short axis is better optimized than that of ellipse

since the former gives a congruent value at long or short-axis

while the other loses the virtue;（4） Compared with this study

traditional researches overestimated the mean intensity

but the difference will dilute with growing distance;（5） Comparisons of this study shows that the intensity prediction decayed fastest in West America

and the next is that in East China.Also

the application of this study is also confined by the distance and magnitude of the earthquake data.This study may provide a fair consideration for micro-zonation and design earthquake ground motion in seismic moderate area.