Probing the structure stability and optical properties of halide perovskites under radiation is of great significance to extend their applications in aerospace and radiation detection. However, the intrinsic radiation stability of perovskites still remains controversial due to the interferences of environmental factors such as moisture and oxygen in air. In this work, we reported CsPbBr 3 perovskite nanocrystals (CsPbBr 3 NCs) that encapsulated in amorphous glass to isolate moisture and oxygen in air, based on which the gamma-ray irradiation effect of these spatial confined CsPbBr 3 NCs was investigated in detail. The results demonstrated that CsPbBr 3 NCs display excellent structural stability accompanied with increased particle size and enhanced photoluminescence after an accumulated dose of 240 krad (Si). This improvement originates form the defect passivation on the perovskite surface under gamma-ray irradiation, which suppresses the nonradiative recombination substantially. Meanwhile, the decomposition of CsPbBr 3 NCs occurred at the dose of 360 krad (Si) and even higher, along with a deteriorated optical performance. This work provided an ideal platform to understand the intrinsic stability of halide perovskites upon radiation conditions. [Display omitted] • Spatial-confined CsPbBr 3 nanocrystals was employed to probe the intrinsic stability of the perovskites upon gamma ray irradiation. • The CsPbBr 3 displayed stable structural and photoluminescence after a gamma ray dose of 240 krad (Si), and then decomposed. [ABSTRACT FROM AUTHOR]