Abstract: A two-stage secondary-flow jet-based fluidic thrust vectoring nozzle is developed to achieve a greater fluidic vector deflection angle based on the single-stage jet fluidic thrust vector control. The principle is to deflect the primary flow once more following the initial deflection, demonstrating the “relay” effect, with the pressure differential created by the two-stage secondary flow. In this study, computational fluid dynamics (CFD) simulation was applied to determine the size of the secondary flow passage opening and the angle of incidence. Under the control of single-stage and two-stage secondary flow jets, the flow control mechanism corresponding to the primary flow vector deflection was investigated through simulation, smoke flow visualization, and pressure measurement experiments. The results reveal that the two-stage secondary flow can cause the primary flow to deflect twice, significantly increasing the primary flow vector’s deflection angle. The maximum primary flow upward vector deflection angle of 12.5° can be produced when the ratio of the output flow of the two-stage secondary flow control slot to the primary flow volume flow is 0.021.