The four-stepmethod of petroleumseismogeology has been widely used in the exploration and development of oil and gas, and achieves good effects. Based on the four-step method of petroleumseismogeology and combined with the characteristics of reservoir study, this paper elaborated the connotation and inner logical relation of the four-step method of seismic reservoir. The result shows that reservoir geological study is the geological basis, seismic petrophysical experiment and technique study are the experimental basis and technique system, reservoir characterization and modeling is the research core, and comprehensive reservoir evaluation and modeling are the results systemof the seismic reservoir. The case study on the seismic reservoir of igneous rock of fissure eruption in Xai 72 well area in Wuxia area confirms the feasibility and effectiveness of the four-step method, the established reservoir characteristic model and 3D reservoir models guide the exploration and development of this area, and provide a good reference for the reservoir characterization andmodeling about igneous reservoir in other areas.