The invention provides a heavy ball circuit type dual-mode electric power steering device which comprises a steering gear shell assembly, an input shaft and screw rod assembly, a toothed fan axle assembly, a support base assembly, a turbine, a worm, an inner end cover assembly, a corner torque sensor, an outer end cover assembly, a spline adapter sleeve assembly and a motor assembly. The motor assembly is taken as a power source, the turbine and the worm are used for transferring the power to the input shaft and screw rod assembly, the input shaft and screw rod assembly is used for outputting torque and angular displacement through the toothed fan axle, and the input shaft and screw rod assembly has two control modes of angle position and torque assistance. In the heavy ball circuit type dual-mode electric power steering device provided by the invention, a large reduction ratio mechanism and the corner torque sensor are adopted for replacing a rotary valve structure in a ball circuit type hydraulic power steering gear, so that without increasing additional space, the conversion from hydraulic driving to intelligent electric driving is realized; and compared with the ball circuit type hydraulic power steering gear in the same volume, the heavy ball circuit type dual-mode electric power steering device has the advantages that the power requirement is reduced by 300% and the maximum output torque is promoted by 5%.