Objective      To determine the effect of simulated fast buoyancy ascent escape on stress status of trainees and investigate the methods to control trainee’s stress.       Methods      Subject (“Anxiety thermometer”) and object (Salvia Chromogranin A

CgA) stress state was measured in simulated fast buoyancy ascent escape in 28 trainees

and 14 trainees received imagery training as intervention. The difference of subject and object stress state was compared between the groups.        Results      The trainee’s subject stress state and object stress state were increasing as the simulated fast buoyancy ascent depth grew (the main effect of subject stress on depth: F=18.283

P

0.01

and the main effect o

f object stress on depth: F=13.283

P

0.01). Imagery training reduced subject stress state (main effect: F=4.585

P

=0.042)

but couldn’t reduce the object stress state (F=0.136

P

=0.715) in simulated fast buoyancy ascent escape.       Conclusion      The trainee’s stress states are influenced by the simulated fast buoyancy ascent depth

and imagery training can decrease the trainee’s stress state in the process.