Abstract: The effect of the additon of RE, Al, Mn on the inclusions and mechanical properties of suspension casting steel is studied. The results show that the morphology,size, and distribution of inclusions in suspension cating steel are improved, and the plasticity,the tenacity of steel are increased by the additon of RE, Al, or Mn during pouring.The effect of RE or Al is more remarkable than that of Mn. RE or Al is reacted with O₂ in molten steel and the large amont of oxide small in size is formed, so that the harmful influence of inclusions is decreased. Wlien RE is added in the form of No.1 RE alloy,the inclusions may accumulate,and the mechanical properties of steel deteriorate.