Abstract: Based on the small magnitude earthquakes and explosions and quick identification requirements, this paper analyzed the identification ability of first motion amplitude AI and P maximum amplitude AP to S maximum amplitude AS ratios. Considering the impact of propagation paths on different seismic amplitude, this paper selected reasonable amplitude attenuation formula with distance, and invesigated attenuation characteristics of P, S amplitudes which indicates that amplitude of explosion attenuated faster than that of earthquake. We chosen 100 km as attenuation correction distance and recalculated the ratios of P amplitude to S amplitude after attenuation correction, then it is shown that the correct recognition rate of AI/AS improved from 84% to 98%, AP/AS improved from 92% to 100%. These results show that amplitude ratio criteria after attenuation correction could be better applied to small magnitude earthquakes and explosions recognition.