Abstract： Objective To select qualified divers for participation in the simulated He-O2 deep saturation dive.Methods Based on the 7 physiological and psychological indicators ( brainstem auditory evoked potential, neurobehavioral function,electroencephalogram, finger tremor, subjective symptoms,physical performance,and heart rate variability ) obtained from the 7 divers during the rehearsing dive to 250 m,the expert grading method was applied to determine the weight d each indicator,and the rank sum ratio was used to generate the composite rating of the capacity of the 7 divers.Results The correlation coefficient between the performance of the 4 divers ( who finally participated in the targeted 480 m-saturation- 493 mexcursion He-O2 deep dive) and the composite rating during the excursion from the 480 m saturation to a depth of 493 m was 1 (P ＜0.01).High pressure nervous syndrome (HPNS) displayed in the 7 divers during the course of compression also verified their former rating.Conclusions By using the expert grading method and the rank sum ratio,the physiological and psychological indicators obtained from the divers during the rehearsing dive could be used to predict divers'performance during exposure to much higher pressures.The composite rating could yet be considered as an effective method for the selection of qualified divers.