The invention discloses 
rare earth steel and a preparation method of the 
rare earth steel. The 
rare earth steel comprises the following components of, in percentage by weight, 0.01%-0.05% of C, 0.15%-0.3% of Si, 0.4%-0.5% of Mn, 8%-10% of Cr, 2%-2.5% of W, 0.2%-0.25% of V, 0.05%-0.1% of Ta, 0.001%-0.01% of Zr, 0.3%-0.6% of Y<2>O<3> and the balance Fe; during preparation, Cr, W, Ta, Fe, Si, Mn andY are smelted into 
metal mother liquor, then 
mixed gas of CO<2> and Ar serving as an 
oxidizing agent is introduced into the 
alloy mother liquor, Y is oxidized into Y<2>O<3>, Zr, V and C are added, 
casting is performed after melting down; electroslag remelting is carried out on a cast 
ingot in a protective 
atmosphere, purifying is carried out; austenitizing is carried out on a purified steel 
ingot,then the steel 
ingot is subjected to pressure 
machining to form a steel plate, 
water cooling is carried out after pressure 
machining; and heat treatment is carried out on the steel plate obtained through pressure 
machining, a 
yttrium nanometer precipitated phase is precipitated from the steel plate, and the rare earth steel is obtained. According to the rare earth steel and the preparation methodof the rare earth steel, RAFM ( Reduced Activation Ferritic  /  Martensitic ) steel can be produced in a 
smelting and 
casting mode, the yield of the RAFM steel can be increased, and meanwhile the high-temperature 
mechanical property of the RAFM steel is improved.