Objective To compare the therapeutic effect of dark plum mixture on rats with radiation?induced xerostomia, given by gastric gavage and oral spray. Methods Rat model of radiation?induced xerostomia were developed by electron linear accelerator. Wistar rats were randomly divided into spray group and gastric gavage group, and normal group, positive control group and normal control group were set up within these two groups. The dark plum mixture was administered for 14 days. After treated for 7 days and 14 days, saliva was collected and submandibular gland samples were collected. The salivary secretion, Sorgan index, component analysis and pathological changes of submaxillary glands between the groups were assessed. Results On the 7thday after irradiation, the saliva secretion and gland coefficient of the dark plum spray group were significantly higher than the positive control group and normal control group ( P < 0.05). The saliva secretion, gland coefficient and saliva amylase activity of the dark plum mixture spray group were significantly higher than the dark plum mixture gastric gavage group ( P < 0.05). On the 14th day after irradiation, the saliva secretion and gland coefficient of the oral spray group were significantly higher than the gastric gavage group ( P < 0.05). The pathological examination of submandibular gland tissues showed that 7 days after irradiation, there were less interglandular space and inflammatory cell infiltration in the oral spray group than the gastric gavage group. On the 14th day after irradiation, the ductal damage and cell nuclear pyknosis in the oral spray group were milder than the gastric gavage group. Vacuolated necrosis and nuclear pyknosis of some glandular cells were visible in the gastric gavage group 7 and 14 days after irradiation. Conclusions Compared with gastric gavage, the oral spray of dark plum mixture increases more saliva and salivary α?amylase secretion, effectively promote the repair of submandibular glandular cells after salivary gland irradiation, and indicates a better therapeutic effect on radiation?induced xerostomia.