Based on the modified Biot′s theory of two-phase porous media, a study was presented on seismic reflection and transmission coefficients at an air-water interface of saturated porous soil media. The major differences between air-saturated soils and water-saturated soils were theoretically discussed, and the theoretical formulas of reflection and transmission coefficients at an air-water interface were derived. The characteristics of propagation and at- tenuation of elastic waves in air-saturated soils were given and the relations among the frequency, the angle of incidence and the reflection, transmission coefficients were analyzed by using numerical methods. Numerical re- sults show that the propagation characteristic of the wave in air-saturated soils is great different from that in wa- ter-saturated soils. The frequency and the angle of incidence can have great influences on the reflection and trans- mission coefficients at interface. Some new cognition about the wave propagation is obtained and the study sug- gests that we may carefully pay attention to the influence of air on the dynamic analysis of seismic wave. Based on the modified Biot’s theory of two-phase porous media, a study was presented on seismic reflection and transmission coefficients at an air-water interface of saturated porous soil media. The major differences between air-saturated soils and water-saturated soils were theoretically discussed, and the theoretical formulas of reflection and transmission coefficients at an air-water interface were derived. The characteristics of propagation and at- tenuation of elastic waves in air-saturated soils were given and the relations among the frequency, the angle of incidence and the reflection, transmission coefficients were analyzed by using numerical methods. Numerical re- sults show that the propagation characteristic of the wave in air-saturated soils is great different from that in wa- ter-saturated soils. The frequency and the angle of incidence can have great influences on the reflection and trans- mission coefficients at interface. Some new cognition about the wave propagation is obtained and the study sug- gests that we may carefully pay attention to the influence of air on the dynamic analysis of seismic wave.