Abstract: Thirty-six Simmental steers (average BW 420 kg, aged 2.5) consuming a corn straw diet were divided into four groups (n=9) randomly and supplemented with four concentrations (0 g/d, 0.45 g/d, 0.9 g/d and 1.8 g/d) of supplemental lanthanum to evaluate the effects of different lanthanum concentrations on nutrients digestibility, serum GSH-px, growth hormone (GH), insulin, T3 and T4 concentration. The results showed that: the digestibility of organic matter, crude protein, ether extract, crude fiber, neutral detergent fiber and acid detergent fiber in group supplemented by 0.9 g/d lanthanum significantly increased by 8.09 %、7.13 %、15.20 %、9.47 %、13.09 % and 20.48 % comparing with control group, and they are higher than control group and other treatments (P<0.05). The serum glutathione peroxidase concentration in group supplemented by 0.9 g/d lanthanum significantly increased by 8.22 U/ml, 3.95 U/ml and 5.04 U/ml compared with control group, 0.45 g/d and 1.8 g/d supplemental lanthanum. The serum GH, insulin, T3 and T4 concentration in group supplemented by 0.9g/d lanthanum were higher than control group and other treatments (P<0.05). It indicated that supplemented dietary lanthanum.