In order to reveal the influences of variable inlet guide vanes (IGVs) on cavitation performance of axial pump under off-design conditions, experiment was conducted in a closed test rig at the Pump Station Laboratory of Wuhan University. Both the operating conditions with and without IGVs and the situations when the angles of IGVs were changed were researched. The angles of IGVs were adjusted by bolts. The cavitation performances were obtained and the unsteady pressure pulsations collected by pressure sensors which installed in pump inlet and outlet were analyzed based on fast Fourier transform. The results showed that when the pump device was assembled with IGVs, pump head was reduced due to more energy losses were induced. However, the cavitation performance was improved. At the same time, the critical net positive suction head was decreased and the cavitation performance was enhanced as the angles of IGVs were adjusted from negative to positive values. The pressure pulsation results showed that when cavitation occurred, pressure amplitude was magnified both in pump inlet and outlet when IGVs were set up, and the pressure peak appeared mainly in blade frequency and its harmonic frequencies as a result of the influence of rotating of impeller. With the development of cavitation, pressure pulsation aggregated in low frequency in inlet and appeared broadband feature in outlet. When mass flow rate was decreased, the pressure amplitude discrepancy shrank and the pressure peak depended on the angles of IGVs.