Abstract: Objective: To systematically evaluate pressure uncler prevention effect of pressure-relief devices for critical patients, and to provide evidence-based references for choosing and using pressure-relief devices. Method: We searched related Chinese and English database, used software to classify, to exclude repeated data, and to eliminate the literatures not meeting the including criteria, read the including articles carefully, extracted and analyzed the data, evaluated research quality to make sure the evidence strength and recommendation level of results. Results: Five articles , including two Randomized Control Trails (RCTs),three non-randomized control trails were recruited in this study from 4 countries and we totally got 716 patients. The methodology quality of five articles were grade B. The six different dynamic alternating air pressure-relieving devices in intervention group can reduce incidence and stage of pressure ulcer for critical patients and were recommended to use. Conclusion: The different pressure-relieving devices played some roles in prevention pressure ulcers for critical care patients, the clinician should think about the available resource and the patients' desire and relative evidence when choosing and using pressure-relieving mattresses.