In order to quick dilute the thermal waste water, the Realizable k-ε turbulence model of Fluent and SIMPLE Consistent method are utilized to investigate the effect of spacing of nozzles and initial velocity of thermal buoyant jet on flow and temperature fields. The research indicates that as the spacing of nozzles increases, the effect of the first jet on the second one gradually decreases, and blending degree of second one increases. The reverse vortex pair generated by the jet and cross flows enlarges the mixing degree of thermal waste water and environmental fluid and the distribution of temperature field of cross section is the same as the shape of kidney. As the initial velocity increases, the decay rate of axis temperature of the first and second jet increases on the condition of same spacing of nozzles. Additionally, the variations of spacing of nozzles has little impact on the dilution degree of axis temperature for the first jet but has sophisticated influence on the second one on the condition of same initial velocity. The conclusion can be drawn that when S/D=2 and the initial velocity increased, we get the optimal solution for quick dilution of thermal waste water in this research.