Objective To explore the biomechanical properties of pig thoracic aorta. Methods 54 pig thoracic aortas aged from 1 to 9 months old were observed by cutting the middle regional vessels into short segments. Thoracic aortas from 7-month-old pigs were divided into three regions: superior, middle and inferior regions and each region was redivided into 5 shorter segments. The equivalent inner diameter and the mean wall thickness were measured after every segment has been cut radially for 20 minutes. Results With age the opening angle of pig thoracic aorta aged from 1 to 7 months old increased from (42.17±4.06)° to (76.22±4.40)°, after 7 th months became stable ,while in the same age pigs the opening angle of thoracic aorta decreased from (99.73±6.79)° in the superior region to (42. 09±7.40)° in the inferior region. The ratio of the wall thickness and the equivalent inner diameter decreased with age and stayed at about 0.18 after 7th months. Conclusion The opening angle, wall thickness and equivalent inner diameter of the studied pig thoracic aortas increase with age, but tend to decrease with the longitudinal distance X/L increasing. The inner and outer diameters increase after 7th months simultaneously. The results are useful for providing essential data for pig→human vascular xenotransplantation and analyzing the pathological recovery and remodeling process.