Objective: To explore the application effects of risk assessment method of failure mode and effect analysis (FMEA) on the limb posture positioning nursing of extremely severe burn patients. Methods: A retrospective observational study was conducted. According to the different limb posture positioning methods, 30 extremely severe burn patients who met the inclusion criteria and underwent routine limb posture positioning in the First Affiliated Hospital of Air Force Medical University from January 2018 to June 2019 were included into routine limb positioning group (19 males and 11 females, aged (40±10) years), and 30 extremely severe burn patients who met the inclusion criteria and underwent limb posture positioning with FMEA risk assessment from July 2019 to December 2020 in the department were included into FMEA limb positioning group (20 males and 10 females, aged (38±10) years). Patients in routine limb positioning group received only routine limb posture positioning by rehabilitation therapists with bare hand every day from the time when their limb wounds healed until they were discharged from hospital. Patients in FMEA limb positioning group received FMEA risk assessment by physicians, rehabilitation therapists, and nurses within 24 hours after admission to analyze the potential failure modes of limb posture positioning, and target-directed limb posture positioning measures were adopted until they were discharged. The risk priority numbers (RPNs) of six major failure modes of patients in FMEA limb positioning group before and after intervention were compared. The range of motion (ROM) of shoulder abduction, elbow extension, wrist dorsiflexion, ankle plantarflexion, total action motion of hand, and modified Barthel index scores of the patients in two groups before and after intervention were also assessed. Data were statistically analyzed with independent sample t test, chi-square test, and paired sample t test. Results: The RPNs of 6 main potential failure modes of patients in FMEA limb positioning group i.e. untimely interference of limb posture positioning, not strong awareness of limb posture positioning of nurses, inconsistent of evaluation standards of limb posture positioning, nurses' lacking knowledge about limb posture positioning, nurses' lacking active participation, unsatisfying effects of patients' limb posture positioning were respectively (146±31), (140±22), (125±34), (136±23), (110±28), and (110±5) points after intervention, which were significantly lower than (578±64), (543±57), (419±89), (269±64), (240±41), and (222±48) points before intervention (t=18.441, 23.681, 10.035, 5.362, 9.438, 7.171, P<0.01). After intervention, the ROMs of shoulder abduction, elbow extension, wrist dorsiflexion, and ankle plantarflexion of patients in FMEA limb positioning group were significantly better than those in routine limb positioning group (t=-4.250, 11.400, -15.928, 10.963, -7.470, P<0.01); the ROMs of shoulder abduction, elbow extension, wrist dorsiflexion, and ankle plantarflexion of patients in FMEA limb positioning group and routine limb positioning group were significantly better than those before intervention (t=-35.573, 33.670, -31.090, 32.902, -19.647, -14.952, 11.411, -33.462, -12.818, -13.672, P<0.01). After intervention, the Barthel index score of patients in FMEA limb positioning group (78±9) was significantly higher than 57±9 in routine limb positioning group (t=-9.055, P<0.01), and the Barthel index scores of patients in FMEA limb positioning group and routine limb positioning group were significantly higher than those before intervention (35±5 and 34±4, t=-22.964, -12.329, P<0.01). Conclusions: In the limb posture positioning nursing of extremely severe burn patients, risk assessment method of FMEA can effectively avoid the high risk factors in the limb posture positioning of patients, thus maintain the effects of limb posture positioning and improve the ROM of patients, as well as increase the daily living ability of patients in prognosis.