Abstract: Objective: To probe into the incidence of transient hypothyroxinemia (THP) in premature infants and to observe their early quality of life. Methods: One hundred and twenty-five hospitalized premature infants were divided into two groups. Group A included 56 premature infants with no other diseases,group B included 69 premature infants who were accompanied by other diseases,and 62 normal neonates acted as control. Electrochemistry luminescence was used to detect the blood thyroid-stimulating hormone (TSH),total thyroxine (TT4) and total triodothyroxine (TT3) of all the three groups on the 1st and 7th day. Results: The incidence of THP was 62.4% in the premature. The concentration of blood TSH,TT4 and TT3 on the 7th day was lower than that on the 1st day in all the three groups. The TSH,TT4 and TT3 in group A and B was lower than that of the control (P < 0.01);the TSH,TT4 and TT3 in group A showed no significant difference with group B on the 1st day (P < 0.01),but the TT4 in group B was lower than that in group A on the 7th day (P < 0.01);the TT4/TSH in the three groups showed no significant difference on the 1st day (P > 0.05),but on the 7th day,the TT4 and TSH in the control group were higher than those in group A and B (P < 0.01). The infants in THP group needed more oxygen,and the time of regular defecation,sustaining of hyperbilirubinemia,heat amounts to 418.4 kJ·kg^-1·d^-1 and restoring birth weight was delayed compared with the control (P < 0.01). Conclusions: The development of the thypothalamus-pituitary-thyroid gland of the premature infants is immature,which will influence their early quality of life.