Abstract: Based on the theory of two-phase media, construct Gassmann fluid factor, which can be achieved on effective oil/water discrimination. Further the corresponding fluid elastic impedance equation is derived from a fluid item involved reflection coefficient approximation formula, take fluid factor into seismic inversion process and directly involved in the process to identify the target reservoir fluid, then achieve a direct inversion fluid factor method, technology and processes from elastic impedance data volume. Direct inversion of fluid factor reduces the error caused by calculating the fluid factor indirectly, which improves the accuracy of seismic fluid identification. In the real data application, the petrophysical analysis showed Gassmann fluid factor is helpful for distinguishing oil and water. The inversion results show that the fluid factor is able to effectively identify target layer of oil and water features, provides a reliable technical support for the next drilling development.