Objective: To investigate the relationship between thyroid dysfunction and blood lipid level. Methods: Two hundred patients with thyroid function problems admitted during April 2013 to March 2015 were enrolled for the study, including 100 cases each with hyperthyroidism or hypothyroidism, and 80 participants undergoing health maintenance examination during the same period served as control. The levels of thyroid hormones and blood lipids in all subjects were measured, and the correlation between their levels was analyzed. Results: By univariate analysis, significant difference was found in all the studied thyroid hormones and blood lipids among the three populations (all P<0.05). Correlation analysis in patients with abnormal thyroid function showed that the level of thyroid stimulating hormone (TSH) had a positive correlation with the levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and apolipoprotein B100 (ApoB10) (r=0.695, 0.714, and 0.632); the level of free triiodothyronine (FT3) had a negative correlation with the levels of TC, LDL-C and ApoB100 (r=–0.769, –0.705 and –0.689); the level of free thyroxine (FT4) had a negative correlation with the levels of TC, LDL-C and ApoB100 (r=–0.728, –0.676 and –0.625) (all P<0.05). Conclusion: Thyroid dysfunction may cause blood lipid metabolic abnormity, which deserves attention in clinical practice.