Serpentine aggregates were selected from Hubei Qichun, Jiangxi Yiyang and Shaanxi Hanzhong (hereinafter referred to as Hubei, Jiangxi, Shaanxi serpentine aggregate). The anti-neutron radiation preference and structural stability at high temperature of serpentine aggregate were studied by scanning electron microscope (SEM), X-ray diffractometer (XRD) and thermogravimetric analyzer (TG). The results show that the crystal water content of Hubei, Jiangxi and Shaanxi serpentine aggregate are 6.89%, 12.55% and 12.50% (mass fraction), respectively. The (10, 16］ and (16, 20］ mm particle sizes of Hubei serpentine aggregates have thermal cracking behavior at 500 ℃, and their thermogravimetric losses are 1262% and 2472%, respectively. Because of Shaanxi serpentine aggregate containing brucite, the brucite is thermally decomposed and dehydrated at 300~500 ℃, and the thermogravimetric loss of the aggregate at 500 ℃ reaches 2.75%~4.04%. At 500 ℃, the maximum thermogravimetric loss of Jiangxi serpentine aggregate is 2.26%, and it has no thermal explosion behavior and the influence of brucite content, and it has a great high-temperature structural stability, which has the best performance of serpentine aggregate from three producing areas. The test method for structural stability of serpentine aggregate with different particle sizes at high temperature is proposed, which has certain guiding significance for promoting the engineering application of domestic serpentine aggregate in anti-neutron radiation concrete such as nuclear power reactors, spallation neutron sources and maintainable test units in nuclear fusion material irradiation facilities.