Abstract: Pumping stations, serving as crucial hydraulic structures, are integral to a variety of application scenarios. The complexity of their operating conditions leads to the presence of suction vortices in the inlet pool, which can impact the safe and stable operation of the pumping station. To study the effect of suction vortex morphology and its evolution on the stability of centrifugal pumps under different operating conditions, a full channel model test platform was built for a vertical centrifugal pump with a horizontal side suction arrangement suction tube as the research object. The VOF(Volume of Fluid) method was used to simulate the flow characteristics. Unsteady flow characteristics of a pump during the evolution of suction vortex at high flow rates and their effects on the steady operation of a centrifugal pump are analyzed. The results show that, during the testing, the time for the steady existence of the suction vortex increases with the flow rate increases, and the shape changes from a surface depression vortex to a continuous suction vortex. At high flow rates, the strength and diameter of the suction vortex increase continuously, resulting in the whole observation time being in the continuous phase of the suction vortex, with the projected area remaining at a high value. At the same time, the shedding of a large-scale bubble caused the projected area to fluctuate violently. The development paths of the suction vortices captured by numerical simulations were in good agreement with the experimental results. The suction vortices first appeared near the wall of the tube, broke off into the suction tube under the action of the incoming flow after being destroyed, and flowed along the bottom of the suction tube to form two air paths and large bubble clusters at the inlet of the centrifugal pump. At high flow rates, as the suction vortex evolved, the air constantly moved toward the centrifugal pump and accumulated, and the air content in the flow passage components peaked during the continuous phase. As the suction vortices evolved from the development phase to the continuous phase, the void fraction rapidly increased, and bubbles clustered in the flow channel of the impeller, causing a sudden change in the pressure pulsation on the suction surface of the blades. The pressure pulsation range in the continuous phase was 2 times that of the development phase, the main frequency of the pressure pulsation was shifted from f_n (rotating frequency) to 2f_n, and the amplitude of the pulsation at 2f_n increased along the flow direction with the enhancement of the gas action while the non-uniform inflow increased dramatically. Large-scale vortices were observed within the channel of the impeller, and the gas velocity was greatest at the leading edge of the blade near the suction tube side. In the rest of the channel, the gas velocity varied from increasing first to decreasing, which caused the amplitude of the radial force on the impeller to increase and the radial force vector to be eccentric. The gas was distributed unevenly in the impeller flow passage and converged at the outlet of the volute after rotating. The peak-and-peak of pressure pulsations in the three regions (vaneless region, guide vane, and volute) all had higher values in specific regions of the centrifugal pump. In the continuous phase of the suction vortex, the bubble moved with the main flow towards the tongue. The gas density is much lower than the liquid density, which prevented the bubble cluster from forming a pressure gradient to occupy the flow channel. This caused a significant increase in turbulent pulsation, accompanied by the expansion of the region of high water turbulent kinetic energy. Consequently, this led to an increase in the peak-to-peak value of the pressure pulsation at the tongue, affecting the operational stability of centrifugal pumps.