Objective:To study the correlation among serum 25-(OH)D3 level and thyroid function,thyroid disease duration,size in patients with Graves disease(GD) or Graves’ ophthalmopathy(GO) or hyperthyroid heart disease. Methods:Totally 150 cases of pa-tients diagnosed with the corresponding diagnosis were selected. All the cases were divided into GD group(n=50),GO group(n=50),HHD group(n=50),and the other 50 cases of healthy people at the same age were selected as the control group(n=50). Then all the cases were taken the morning fasting venous blood,in which the FT3 and FT4,TSH,TRAb,TPOAb,serum 25-(OH)D3 were tested. The study of 25-(OH)D3 level takes the rule of the international consensus for references:serum 25-(OH)D3 level< 20 ng/mL means vitamin D deficiency,and serum 25-(OH)D3 level 20-30 ng/mL means vitamin D is not enough,when the level ≥30 ng/mL suggests vitamin D is sufficient. All the data were analyzed by SPSS 17.0 statistical software,and the significant inspection standards is P<0.05. Results:①Compared with the control group,serum FT3,FT4,TPOAb,TRAb levels were significantly increased(P=0.000),and TSH,25-(OH)D3 levels were significantly decreased in GD group,GO group and HHD group(P=0.000). There was no significant difference in serum FT3,FT4,TPOAb,TRAb and TSH among GD group,GO group and HHD group(P>0.05). Serum 25-(OH)D3 level was sig-nificantly lower in GO group and HHD group than in GD group(P=0.000),and no statistical significant difference was ob-served between GO group and HHD group(P=0.320). ②The serum 25-(OH)D3 levels in group GO were significantly positively correlated with FT3(r=0.390,P=0.006) and FT4(r=0.40,P=0.004),but there was no statistically significant corre-lation with TSH(P>0.05). There was no statistical correlation between the remaining groups(P>0.05). Conclusion:The low level of 25-(OH)D3 maybe closely related with the pathogenesis of Graves disease and its complications,and the deficiency of serum 25-(OH)D3 may also be involved in the development and progression of GO and HHD.