Objective To observe the effect of combination of selenium,Youguiwan and levothyroxine sodium on primary hypothyroidism.Methods 120 patients with primary hypothyroidism were randomly divided into two groups.Patients in control group(n=60) were treated by levothyroxine sodium.60 patients in treatment group were treated by combination of selenium,Youguiwan and levothyroxine sodium.The therapeutic course was six months in two groups.The clinical effect,thyroid hormone levels and antibody changes were observed before and after treatment.Results The total effective rate in treatment group was 94.2% and 80.5% in control group.There was significant difference between two groups on the total effective rate(P0.05).The levels of FT3 and FT4 after treatment were increased as compared with those before treatment in two groups,the levels of TSH,TGAb and TPOAb were decreased(P0.05,P0.01).There was significant difference between two groups on FT3,FT4 and TSH(P0.05,P0.01).Conclusion Combination of selenium,Youguiwan and levothyroxine sodium has a definite therapeutic effect on primary hypothyroidism.