Some dynamical characters and seismic liquefaction of schistose grain sand are very complex and different to that of the round grain sand; We may reduce the degree of liquefaction if by using the method of code without considering the characters of schistose structure. A new empirical formula of Ncr is suggested to evaluate the seismic liquefaction of subsoil of a metro with considering the schistose structure of Nanjing's sand. According this new method the index of liquefaction of subsoil of a metro section from Xuanwumen station to Nanjing station is middle degree

The distribution of affect-coefficient and index of liquefaction are also described with depth. It is important to take care of the schistose structures to analyze the seismic liquefaction in Nanjing; this result is testified to be correct by dynamical test; the research can improve the accuracy of evaluation.