Based on the concept of radial turbine with adjustable elastically restrained guide vanes(ERGV), the internal flow field of ERGV turbines under pulsating intake conditions was analyzed in detail and the reasons of macroscopical performance changes were studied by using FSI(Fluid-Structure-Interaction) method. The results show that the following adjustment of ERGV changes the rotation angle of guide vane and the airflow angle. At the phase angle of 90°, the total pressure loss coefficient for the stator of ERGV turbine is larger than that for the original turbine, and the separation intensity at the inlet of ERGV rotor and the entropy at the outlet of rotor blade is larger than that of original turbine respectively. At the phase angle of 270°, the stator and rotor channel losses of ERGV turbine are smaller than those of original turbine. The difference between the low pressure pulse period and the high pressure pulse period ultimately leads to a slight decrease in the efficiency of ERGV turbine, but the flow capacity improves and the output power increases.