The utility model discloses an impeller of inner thrust low impedance water flow generator, which belongs to the sea current, wave, river or tidal force power generation processing technology field. The impeller is characterized in that: a blade mounted between the upper and lower disc is controlled to swing inwards the impeller by an angle no larger than 90 degrees for reducing resistance by a shaft type angle limiter disposed on the shaft head position of the blade, when the blade is acted by the front water flow; thereby, the water flows from outside into the impeller, a very high hydraulic pressure is formed inside the impeller, the pressure cuts out from inside of the impeller and generates a strong inner thrust to the blade to promote the impeller to run; thus, the sea current, wave, river or tidal force is converted into mechanical force for driving the generator to run for power generation. Characteristics: the impeller compensates the defects of prior arts, can improve the utilization efficiency of converting water flow into mechanical force by above 80%, and provides technology guarantee for manufacturing inner thrust low impedance water flow generating set.