The invention discloses a continuous steel casting process with a function of electromagnetic excitation compound mechanical stirring. According to the process, when alloy melt solidifies, microscopic and macroscopic strong shear flows are generated to break dendritic crystal by the electromagnetic excitation compound mechanical stirring technology, and accordingly, solidification structure refinement, full-equiaxed crystallization and solute segregation reduction are achieved, and alloy properties are improved. The invention further provides a continuous steel casting device mainly comprising a crystallizer, a rotor stirring paddle, a wheel, a program control motor, a magnetic field generator, a coil, and a voltage-regulating frequency-modulating alternating current source. The microscopic flows generated by electromagnetic excitation and macroscopic flows generated by mechanical stirring form complex chaotic flows which form strong shear flows to brake the dendritic crystal, crystal nucleus proliferation is prompted, temperature gradient is reduced, and ultrafine full-equiaxed crystal structure is achieved; meanwhile, segregation of alloy elements is significantly reduced or completely suppressed. The continuous steel casting process and method has the advantages that the energy consumption is significantly lower than that of conventional electromagnetic stirring and energy conservation is significantly effective.