Abstract: Doing seismic inversion was a general task during petroleum and natural gas prospecting and developing.Inversion was a key technique for reservoir forecasting. We could forecast the transverse distribution of reservoirs, if the impedance of P-wave was in good correlation with the lithology. But, if the correlation was complicated, elasticity impedance inversion was needed to forcast reservoir and its petroleum and natural gas. The elasticity impedance inversion result from Ya13-1 gas field shows that the resolution of elasticity impedance inversion profiles was higher based on P-wave seismic data.The P-wave impedance difference was greater than S-wave impedance between the gas reservoir and the caprock of the reservoir. The elasticity impedance inversion data were used to find residual gas, mud interlayer and gas-water interface. It helps us heighten the recovery ratio. Because the resolution of conversion-wave seismic profile was lower, its resolution of the elasticity impedance inversion profile was also lower based on four components seismic data.