Objective: To establish a rating scale for assessing severity and activity of pretibial myxedema (PTM) and to validate its application value by ultrasonic measurement of skin thickness and detection of thyroid stimulating hormone receptor antibody(TRAb). Methods: The PTM severity and activity rating scale was established based on Vancouver scars scale and PTM skin lesion staging. A total of 40 PTM patients were enrolled during January 2015 to December 2018 and severity and activity of PTM referring to the clinical manifestation and skin lesion were assessed. The correlation of scale score with serum TRAb level and skin dermal thickness in the lesions measured by ultrasound were further analyzed. Results: Scores of PTM severity and activity rating scale ranged from 3 to 11, with an average of 7.2±1.9. The serum TRAb level in all patients were higher than normal (<1.75 IU/L): 31 cases (77.5%)> 40 IU/L, 7 cases (17.5%) between 30-40 IU/L, and 2 cases (5%) between 20-30 IU/L. The skin dermal thickness obtained by ultrasonic measurement ranged from 4.2 to 10.4 mm, with an average of (6.4±1.6) mm. Spearman analysis showed the rating scores had a positive correlation with serum TRAb level (P<0.05) and skin dermal thickness (P<0.05). Conclusions: The pretibial myxedema severity and activity rating scale is a valua-ble method to assess the degree of PTM severity and activity, and was also easy and helpful to describe the disease accurately.