Objective To investigate the factors influencing the casualties caused by combat stress reaction during sea warfare and their priorities, so as to provide evidence for predicting naval combat stress attrition. Methods The consultation experts of military medical psychology and military health service were selected for a two rounds of expert questionnaire survey; the quantitative index system was established by using Delphi method. Names and meanings of each index were revised according to the experts' suggestions after two rounds of consulting.The weights of each index were also determined by experts' evaluation. Results The recovery rates in the two rounds of questionnaire consultation were both 100%. The level of expert authority was all over 0.8.The index weight system was set up for factors influencing combat stress attrition during sea warfare, including 3 primary indices, 11 second level ones and 51 third level ones; and the weight of each index were also determined. Conclusion The established system in this study may provide a foundation to predict the combat stress attrition during sea warfare and is helpful for more effective medical service.