The seismic inversion in present is all based on the geology information from drilled wells but the seismic prediction of reservoirs is still difficult in those areas where no or less wells drilled. The use of the inversion of mixing pre-stack with post-stack to realize the inversion with virtual wells can solve the problem of less well information. This method takes full advantage of high resolution in pre-stack inversion with high efficiency and high anti-noise ability in post-stack inversion. By principle of genetic algorithm, the way that fine pre-stack full-wave inversion can be done at selected control points to construct virtual wells and then these virtual wells as restricting information are applied in post-stack impedance inversion can realize the reservoir prediction. By this way, the mixing seismic inversion is well practised to the oolitic reservoirs without wells in the slope belt in Longgang area, Sichuan Basin. It is proved that the technology of virtual-well constrained seismic inversion is effective to predict reservoirs in immature areas without drilled wells.