In order to improve the mixing efficiency and reduce the mixing time, a plurality of nozzles with different installation angles should be selected in the process of gasoline blending. Based on the gasoline physical parameters requirements, nozzle jet model and five kinds of gasoline blending schemes are built to simulate the mixing flow field. Combining the standard turbulence model and the sliding grid technique, the numerical simulation and process optimization is done with the commercial Fluent software. The attenuation curves of the nozzle axis radial velocity at the landscape orientation, of the dynamic pressure at the transverse jet center, the velocity distribution curve of the interface and the velocity contours of every mixing flow field are studied. The injection performance of the nozzles and mixed characteristics of the RJM system is finally worked out to get the density- mixing time rules.