To observe the distribution of occupational activity disorders of extremely severe mass burn patients in recovery period after injury. From December 2014 to December 2015, 65 extremely severe burn patients conforming to the inclusion criteria involved in August 2 Kunshan factory aluminum dust explosion accident were admitted to Kunshan Rehabilitation Hospital. They received comprehensive rehabilitation treatment after burns, including wearing pressure clothes, ultrasound treatment, semiconductor laser and red light irradiation, motor function training, and so on. Over 2 years after injury, a cross-sectional survey was conducted on the patients' occupational activity disorders. Modified Barthel index (MBI) was used to assess the degree of activities of daily living (ADL) disorder of patients and to grade the independent level of completing each item of MBI, and then the independent level of patients completing self-care MBI items (bathing, dressing, grooming, eating, going to the toilet, urine control, and stool control) was compared with that of mobility items (going up and down stairs, bed and chair transfer, and walking). The Canadian Occupational Performance Measure (COPM) was used to assess the distribution of occupational activity disorders of patients. The distribution of the five most serious occupational activity disorders was counted, then the frequency and probability of which with frequency greater than or equal to 16 times were calculated. Data were processed with Pearson Chi-square test. Over 2 years after injury, the MBI score of patients was (76±22) points, and the ADL of 83.08% (54/65) patients reached completely self-care or light ADL disorder level. The MBI items arranged according to the completing independent level of patients from high to low were urine control/stool control, walking, bed and chair transfer, going up and down stairs, going to the toilet, eating, grooming, dressing, and bathing. The independent level of patients completing self-care MBI items was lower than that of mobility items ((2)=62.298, <0.001). Over 2 years after injury, the five most serious occupational activity disorders in COPM dimension were mainly concentrated in the self-care dimension, accounting for 55.38% (180/325), followed by 22.46% (73/325) of production activities and 22.15% (72/325) of recreational activities, and the centrally distributed item was the personal self-care item under self-care dimension, accounting for 42.46% (138/325). Over 2 years after injury, the five most serious occupational activity disorders with frequency greater than or equal to 16 times were dressing and undressing, bathing, perineal cleaning, wearing pressure clothes, caring for children, visiting relatives and friends, 31, 25, 16, 17, 18, and 22 times respectively, with a probability of 47.69%, 38.46%, 24.62%, 26.15%, 27.69%, and 33.85% respectively. Over 2 years after injury, most of the patients with extremely severe burns caused by the aluminum dust explosion were completely or basically self-care in their daily life. The disorder of self-care ADL was more serious than that of mobility, and the disorder of individual self-care activity was still the most serious occupational activity disorder of patients in this stage. Chinese clinical trial registry, ChiCTR-OOC-16009188.