The spring steel 60Si2Mn and stainless steel 1Cr18Ni9Ti are employed as experimental materials fabricated by electromagnetic stirring. The microstructural evolution and the plastic rheological mechanism are studied under macroscopic and microscopic condition. The axial compression test is carried out by using Gleeble-1500 thermal-strain-stress simulator. The rheological regular pattern and model are summarized during deformation. The studies show that the flow stress of semi-solid steels at the liquid-solid zone is relative low, no other than 10 similar to 20MPa. The flow stress decreases with the deformation temperature increasing, the soften phenomenon appears with the deformation proceeding and the influence of deformation rate on the flow stress is comparative complex. The deformation behavior of solid phases and liquid phases is different. The microstructural morphology has close relationship with the deformation temperature, the deformation degree and the deformation rate. At the same time, the flow stress expressions are obtained, which represents the relationship between the flow stress and solid fraction, deformation temperature and deformation rate, and so on.