The dry seeds of perillafrutescens(L.) were irradiated with12C6+ ion beams with a dose of 0, 40, 80, and 120 Gy, respectively, at a dose rate of 4 Gy/min generated from the Heavy Ion Research Facility in Lanzhou (HIRFL). The results showed that M1 generation quality characteristics of perilla seeds had some changes after irradiation with 12C6+ ion beams, such as crude protein yields decreasing while total sugar content increased. The iodine value decreased while the saponification value increased, but the acid value, peroxide value and colour of perilla-oil had little change. Furthermore, these findings suggested that carbon ion beam irradiation increased the contents of oleic acid, and decreased the contents of palmitic acid, lauric acid, stearic acid and linolenic acid, but hardly affected the contents of linoleic acid. All these data suggest that 12C6+ ion beam irradiation could increase the "degrees of unsaturation" of perilla-oil to improve its quality, although it had little effect on the physic-chemical quality of first generation perilla-oil.Cited