Abstract: The experimental result of the irradiation of 60Co gamma ray to "Tianbao Banana" showed that the sensitivities of tube-buds the diferent size to 60Co gamma ray were quite discrepant, of which the longitudinally dissected tube-buds of 2.0-5.0 mm were the most sensitive, the 2.0-5.0 mm buds were the next and the 5.0-10.0 mm buds had the laest sensitivity.Their semi-lethal doses were 49.299Gy, 57.431Gy and 68.191Gy respetivdy.The growth weight and proliferation quantity of experimental tube-buds after irradiation had obvious negative correlation to dose leves.Their rdative coefficents(r) were -0.879 and-0.906 respectively.