Aiming to obtain deep insight into the cavitating flow characteristics inside an inducer, a series of experiments were performed to achieve the inducer macroscopic performance, cavitation development and the corresponding pressure fluctuation characteristics. It was found that the breakdown occurred earlier at larger flow coefficient, but there was one flow coefficient at which the inducer had the best cavitation performance. As the cavitation number decreased, the cavities occurred in the leakage vortex firstly, and the leakage vortex cavitation was connected with the shear cavitation in the leakage flow, forming a stable leakage cavitation. And the size of cavitation area was larger at smaller flow coefficients. The amplitude of pressure fluctuation near the tip was increased with the increase of cavitation area, and the blade passing frequency was the dominant frequency as the cavities were distributed symmetrically. As the cavitation number decreased further, several cavitation instabilities occurred, such as the backflow vortex cavitation and synchronous rotating cavitation, which would induce large amplitude pressure vibration and head degradation partially. The former one was developed from the leakage cavitation under heavy blade loading conditions, the later one was attributed to the unsymmetrical cavities without propagating in the circumference direction. With cavitation further development, axial flow instability occurred at larger flow coefficients, which was corresponding to the cavitation surge, and caused by the synchronous variation of the cavities on the three blades. When the cavities were stretched to the outlet of the inducer, the outlet flow angles were affected, the inducer lost the work ability, and cavitation breakdown occurred.