In this paper，amplification coefficient ( ks ) of peek ground motion with different exceedance probability in types Ⅱ and Ⅲ sites，Shandong Province was estimated by analyzing the data of seismic response of soil layer from 358 and 140 drills from types Ⅱ and Ⅲ sites separately. From the results，one can conclude that: (1) the scatter plot of ks data shows that it generally obeys normal distribution; (2) ks decreases with the increase of the strength of incident ground motion，a phenomenon more apparent in type Ⅲ sites than in type Ⅱ sites; (3) for type Ⅱ site，with the increase of depth of the top surface of bedrock where ground motion incident，ks would increase gradually to a stable value until it reaches a depth up to approximately 20 meters or larger，while type Ⅲ site ks is normally insensitive to the depth; (4) the average of ks for type Ⅱ site is 1. 47，slightly larger than that used in the Seismic Ground Motion Parameter Zonation Map of China ( GB18306 － 2001 ) ． The paper also discusses the rectified value of ks for different strength of incident ground motion in type Ⅱ and Ⅲ sites in Shandong Province．