Objective To study the correlation between serum lipids and thyroid function after withdrawn of thyroid hormone in the patients with differentiated thyroid cancer .Methods One hundred and thirty cases of differentiated thyroid carcinoma treated by operative therapy in our hospital form August 2014 to August 2015 were selected .Serum FT4 ,TSH ,FT3 ,triglyceride ,total cho-lesterol ,LDL-C ,HDL-C indexes were detected before discontinuation of levothyroxine sodium (L-T4) ,before operation and 3 weeks after drug withdrawn .Thus the correlation between blood lipid levels and thyroid function was analyzed .Results The HDL-C and the TSH level was positively related before operation (P<0 .05) ,other indexes had no obvious correlation with thyroid function (P>0 .05);the blood lipid levels after medication withdrawn had no obvious correlation with thyroid function (P>0 .05);the total cholesterol levels after medication discontinuation had negative correlation with FT 3 and FT4 levels(P<0 .05);HDL-C was nega-tively correlated with FT3 and FT4 levels(P<0 .05) ,and positively correlated with TSH level (P<0 .05);LDL-C was negatively correlated with FT4 (P<0 .05) .Conclusion When the application treatment of thyroid hormone is suspended ,with the TSH level increase ,the HDL-C level has somewhat elevation ;total cholesterol ,HDL-C and LDL-C levels are negatively correlated with FT 3 and FT4 ,after discontinuation of medication withdrawn ,the blood lipids metabolism abnormality is closely related with thyroid function decline .