Abstract: To investigate the effect of hypothyroidism on liver function in patients with differentiated thyroid cancer after operation before ¹³¹I-treatment, thus providing the reference basis and guiding the treatment plan for the occurrence of liver function abnormality in such patients, a total of 258 patients with differentiated thyroid cancer were retrospectively analyzed who had carried out radical resection of thyroid carcinoma at endocrine surgery and were treated by ¹³¹I at the department of nuclear medicine in the first affiliated hospital of Chongqing medical university. The liver function indexes of preoperative and postoperative before ¹³¹I treatment and the correlation parameters of thyroid stimulating hormone (TSH) categories were comparative analyzed. In addition, correlation analysis was carried out between liver function indexes and serum thyroid function test indexes. The results showed that postoperative liver function indexes before ¹³¹I treatment all were higher than preoperative, there was significant difference (P＜0.001). The comparison of correlation parameters of different TSH groups indicated that there had no significant difference in age, albumin (Alb), total bilirubin (TBil), alanine transaminase (ALT), aspartate transaminase (AST), lutamyl transferase (GGT) and fasting glucose indexes respectively (P＞0.05). However, only direct bilirubin (DBil), alkaline phosphatase (ALP) indexes of different TSH groups had significant difference (P=0.022, 0.016), and ALP indexes were decreased with the increasing of TSH indexes. Correlation analysis showed no significant correlation between liver function indexes and serum thyroid function test indexes. The hypothyroidism in differentiated thyroid cancer after operation before ¹³¹I treatment could result in mild liver abnormalities, but there was no linear correlation between liver function parameters and serum thyroid function detection indexes. Liver function would not exacerbated with the increase of hypothyroidism.