Abstract: The flow-field structure and mechanical characteristics of dual impinging jets are critical issues during the takeoff and landing phases of aircraft. However, the unsteady characteristics of the fountain effect induced by dual impinging jets have not yet been sufficiently investigated. In this study, a dual impinging jet configuration with a nozzle pressure ratio of 1.39, an impingement distance of three nozzle diameters, and a nozzle spacing of 4.8 nozzle diameters is considered. Particle image velocimetry (PIV) experiments combined with numerical simulations are employed to analyze the dynamic evolution of the fountain flow field, and proper orthogonal decomposition (POD) is used to identify the dominant flow structures. The results show that the fountain motion is mainly characterized by lateral oscillations, accompanied by small-amplitude vertical fluctuations. Due to the blocking effect of the upper plate, the lateral oscillation of the fountain is suppressed to a certain extent, and an unsteady oscillation mode is induced, thereby altering its oscillation frequency. From a three-dimensional perspective, the fountain originates from the stagnation line and expands upward in a fan-shaped manner. As the flow develops away from the symmetry axis, a relatively high velocity is maintained initially, but the upward momentum rapidly decays to zero beyond a certain distance.