<p>This paper aims to elucidate the vortex evolution characteristics generated by the tongue of the semi-spiral suction chamber and its influence on the cavitation of the pump. Based on the turbulent viscosity correction model, the internal flow of a centrifugal pump with a specific speed of 160 was simulated, and experimental data verified the simulation. This study focuses on analyzing the conditions of large flow rate, high-efficiency, and partial flow rate. The results show that the tongue will induce a tongue-induced vortex. The tongue-induced vortex extends from the tongue region to the impeller region, and its shape is curved and slender. The shape and volume of the tongue-induced vortex are related to the flow rate. The vortex’s shape is blurred and small in the partial flow rate. There is a complete and obvious curved slender vortex in the high-efficiency zone. In large flow conditions, the vortex’s shape is consistent with the high-efficiency zone and the volume is larger. The vortex’s strength is positively correlated with the circulation of the inlet, which is in the suction chamber. The tongue-induced vortex affects the distribution position of the low-pressure zone on the blade, thereby promoting the leading edge cavitation.</p>