Objective To explore the application of activities of daily living （ADL） scale in mild psychiatric impairment assessment under the guideline of Classification of Human Body Disability Caused by Injury. Methods A total of 124 subjects with organic mental disorders and mild psychiatric impairments （levels 7 to 10）, and 106 healthy controls were included in. All participants were assessed by the ADL scale, physical self-maintenance scale （PSMS） and instrumental activities of daily living （IADL） scale. The difference between the scores of control group and study group, and the relationship of impairment level and the scores were compared, and the threshold value was determined according to the ROC curve. Results The total scores of ADL, IADL and PSMS were significantly different between the control group and the study group （P<0.05）. The scores of ADL, IADL, PSMS were significantly different among the impairment levels （P<0.05）, which showed a relativity with impairment level. The scores of ADL corresponding to levels 10, 9, 8 and 7 were 14-17, 18-23, 24-29 and 30-34, respectively, which showed a good correlation between the conclusion according to the scale and the expert’s opinion （κ= 0.914, P<0.05）. Conclusion The score of ADL was significantly related to mild psychiatric impairment, and the higher ADL score represents the more severe disability, which can be used as a reference index for preliminarily judging the level of mild psychiatric impairment.