Abstract: For fluid identification of carbonate cave reservoir,based on the seismic data by physical modeling,cross plotting is carried out on the elastic attributes obtained from prestack AVO inversion and prestack simultaneous inversion.A cave physical model fullfilled with different fluids (gas,oil and water) is constructed to acquire ultrasonic seismic data.Prestack AVO inversion and simultaneous inversion are adapted on the seismic data to obtain elastic attributes,such as AVO intercept P,AVO gradient G,P-wave impedance Z_P,S-wave impedance Z_S and Poisson?s ratio σ.Then these elastic attributes are analyzed by cross plotting with each other.Three areas of different fluids (oil,gas and water) are marked out on crossplots and then projected to an inversion profile to identify fluid within caves.Results verify that fluid identification by cross plotting analysis of P-G, Z_S -σ,μρ-σ and λρ-σ is good,which can be effectively applied to fluid identification in carbonate cave reservoir.