〔Abstract〕 Objective To evaluate the clinical outcome of131Ⅰ therapy in papillary thyroid Cancer(PTC) with preablative stimulated thyroglobulin(ps-Tg)below 10 μg/L and explore correlation between ps-Tg level and the clinical outcome. Methods Ninety eight PTC patients with ps-Tg below 10 μg/L were selected and divided into four groups [excellent response(ER),indeterminate response(IDR),biochemical incomplete response(BIR) and structural incomplete response(SIR)] according to the response to initial131Ⅰ therapy. BIR and SIR were classified as incomplete response(IR).The clinicopathological features and ps-Tg level were compared among the three groups. Three groups of patients were further divided into ER and non-ER groups and the ps-Tg level was compared between them. Lastly,the optimal cut-off point was obtained by analyzing ROC curve to explore the value of ps-Tg for predicting excellent response(ER). Results There was no significant difference in age,sex,neck ultrasound,recurrence risk,number of lesions,cervical lymph node metastasis and tumor size among the three groups(all P>0.05),but there was significant difference in ps-Tg level among them(P<0.001). Two comparisons further made between groups in ps-Tg level,and there was significant difference between ER and IDR(adjusted P=0.001),IR(adjusted P=0.015),but there was no significant difference between IDR and IR(adjusted P=0.869). There was also significant difference in ps-Tg level between ER and non-ER(P<0.001). Area under the ROC curve was 0.777. The diagnostic optimal cut-off point was 1.95 μg/L,with a higher sensitivity and specificity(80.00% and 70.00%,respectively). Conclusion Ps-Tg of no more than 1.95 μg/L can be used to indicate satisfactory clinical outcome in postoperative PTC patients whose ps-Tg was below 10 μg/L.