Aim To investigate the relationship among thyroid hormone levels, the severity of coronary artery disease and cardiac function in type 2 diabetic patients with normal thyroid function. Methods 415 patients with coronary heart disease (CHD) were diagnosed by coronary angiography. 131 cases were accompanied with type 2 diabetes mellitus (T2DM group) while 284 cases were not (control group). Biochemical indices, thyroid hormone levels were measured and Gensini scores were calculated. Color Doppler examination was followed to evaluate cardiologic parameters, cardiac function and intima-media thickness (IMT). All the type 2 diabetic patients were divided into≤15 Gensini score group (n＝34), 16～42 Gensini score group (n＝33) and ≥43 Gensini score group (n＝64), the above indicators were measured. Multiple linear regression was performed to analyze the relationship between hyroid hormone levels and Gensini score. ResultsT2DM group had higher Gensini score, heart rate, FBG, HbA1c,TG, BUN, MPV, IMT, LVDd and LVPWT than control group with statistically significant differences, while the blood level of FT3, LVEF were significantly decreased (P all＜0.05).FT3 was significantly decreased in contrast to the increment of Gensini score (P＜0.05). FT3 was significantly lower in ≥43 Gensini score group than that in ≤15 Gensini score group. Multiple linear regression analysis demonstrated that HbA1c, Cr, ALT, TG, LDLC and TSH were the independent risk factors for Gensini score. TSH was negatively correlated with E/A (r＝－0.128, P＝0.013), FT4 was positively correlated with IMT (r＝0.113, P＜0.05). Conclusion TSH could be used as an independent risk factor for the severity of CHD. FT3 level is not related to the severity of CHD, but type 2 diabetic patients with low FT3 level should attach importance to cardiovascular events.