Objective:To evaluate the thermal insulation performance of a new fast buoyant ascent escape suit in a specific low temperature environment，so as to provide a basis for the subsequent development of the suit and determining the stand-by time on the surface for rescue.Methods:Five subjects in new fast buoyant ascent escape suits were placed in a low temperature environment with water temperature（-1.0 ± 1.0）℃，air temperature（-2.0 ± 1.0）℃ and wind speed（9.0 ± 0.2）m/s . The changes of core body temperature，average body surface temperature，and heart rate were observed，and the participants’ subjective feelings and tolerance periods of time were recorded.Results:The core body temperature，average body surface temperature，and heart rate of the 5 subjects were within normal range. The tolerance periods of time were all more than 6 h，and the longest period of time reached 6.5 h.Conclusion:The thermal insulation performance of the new fast buoyant ascent escape suit can be maintained for more than 6 hours in a specific low-temperature environment，which meets the design requirements.