Abstract: The ultrastructure of ⁶⁰Co-γ irradiation with different doses on chloroplast and mitochondrion of Panax notoginseng was observed by transmission electron microscop (TEM) and the effects of ⁶⁰Co-γ irradiation on the ultrastructure were studied, aimed at providing theoretical basis for notoginseg irradition breeding. The results showed that: (1) without irradiation, the notoginseng leaf cells’ shapes were normal and had many chloroplasts, there were many orderly grana lamellas and stroma lamellas, which led to strong photosynthesis capacity; mitochondria with complete double membrances were full of strong matrix and tubular cristae could be clearly observed; (2) when the irradiaion dose was 10 Gy, the ultrastructure of chloroplast and mitochondria changed, while they were affected to a lesser degree; the chloroplast membranes were damaged slightly, the structures of internal grana lamellas and stroma lamellas were not affected basically and there had more and bigger starch grains; the structures of most mitochondria were integrity and the number had slightly increased, which showed that the mitochondria had better tolerance to ⁶⁰Co-γ irradiation than chloroplasts; (3) the study also indicated that the damage degree of the ultrastructure of chloroplast and mitochondria became more serious with the increase of irradiation dose. When the irradiation dose was 40 Gy, a large number of chloroplasts disintegrated, vacuoles appeared in great numbers and were connected into a big holes, the results inevitably affected chlorophyll content and light reaction, thereby significantly weakened the intensity of photosynthesis; internal degradations of some mitochondria were serious and some even had completely vacuolization, mitochondrial number was significantly reduced, meanwhile, the structure and function of mitochondria were severely damaged irreversibly with serious cell senescence. It might be concluded that there were different damages in the ultrastructure of chloroplast and mitochondrion of Panax notoginseng leaves by ⁶⁰Co-γ irradiation, but proper radiation could increase the number of mitochondria. The above conclusions could provide theoretical basis for notoginseng breeding of different purposes and theoretical reference for choosing the most appropriate irradiation dose of mutation breeding.