Objective To study the correlation between TSH decrease and post‐stroke depression .Methods 101 patients with acute brain infarction in our hospital from October 2012 to July 2014 were collected as the study subjects and divided into the TSH decrease group and the TSH normal group according to whether serum TSH levels less than 0 .27 uIU/mL .The two groups were evaluated on admission by the National Institute of Health Stroke Scale (NIHSS) ,at 3 months after discharge by modifies Rankin′s Scale(mRS)and the Hamilton Depression Scale(HAMD)respectively .Results The HAMD scores at 3 months in the TSH decrease group were significantly higher than those in the TSH normal group (16 .04 ± 3 .34 vs .14 .03 ± 3 .47 ,P=0 .000)and the mRS scores NIHSS score were significantly higher than those in the TSH normal (3 .2 ± 1 .1 vs .2 .1 ± 1 .5 ,P<0 .05)) .The ra‐tio of poor prognosis in the TSH decrease group was higher than that in the TSH normal group (89 .3% vs .38 .4% ,P<0 .05) ,in‐dicating that the prognosis in the TSH decrease group was poor .Conclusion The correlation could exist between the decrease of TSH level with post‐stroke depression .In acute brain infarction ,the patient with low TSH level could have the poor prognosis .