An aim is a scientific search of possibility of replacement of mechanical drive of rotation of rotor thrower of earthmover on hydraulic fluid power and determination of his dynamic descriptions on the basis of mathematical model, that examines the modes of starting, set motion, and his sudden stopping for an insuperable obstacle from the side of the poured out soil. Method. Static calculation of by hydraulic fluid power on the basis of researches descriptions of loading of working organs of earthmovers and dynamic calculation with the use of package applied programs of VisSim. The mathematical model of hydraulic fluid power includes the imitation modules adjusting of serve of axial piston pump and change of moment of resistance on the modes of starting of hydromotor at idling motion, normal ladening of rotor thrower and sudden stop. Results. For by hydraulic fluid power of rotation of thrower of earthmovers machine can be applied gerotor hydromotors with the swept volume to 200 cm3, and also high-speed axial piston hydromotor with reducing gears. Necessary on the displacement gerotor hydromotors are mass-produced by the row of foreign firms. The calculation of dynamics of hydraulic fluid power showed that at the critical mode of sudden stop of rotor thrower at his hit on an insuperable obstacle from the side of soil, there are attenuation pressure fluctuations. The worked out program of design can be substantially used for the use of other values of loading and frequency of rotation of hydromotor. Conclusion. Results undertaken studies can be drawn on at development of earthmovers of new generation at substituting of mechanical drive of rotor thrower by hydraulic fluid power.