Abstract: By applying the site condition correction models of the next generation of attenuation (NGA) relationships, the equivalent rock site (<>V_s30 = 500 m) ground motion from ground motion records at non-rock site (<>V_s30 < 500 m/s) is calculated. The obtained equivalent rock site ground motions show consistency with the available true rock site records statistically. It concludes that this transformation method is applicable for calculating the equivalent rock site ground motion from non-rock site records. Furthermore, the obtained equivalent rock site ground motion data can reduce the non-coherency in the data from an earthquake event with abundant records, as well as improve the spatial data distribution in the data from an event with limited true rock site records. The equivalent rock site ground motion data obtained from the ground motion by this transformation method may help overcome the barriers in some researches due to limited data distribution. Finally, the limitations and some factors needing further investigation in this method are also discussed.