Objective To study the pathological changes of lungtissues during fast floating escape-induced decompres-sion sickness.Methods Eighty male SD rats were randomly divided into 2 groups, 60 in fast floating escape group (escape group) , and 20 in control group .Rats in the control group were only put in a cabin under the same atmospheric pressure (ATM).Rats in escape group were pressurized to 1.5 MPa by pressureair at the 2t/7 exponential rate and stayed for 4 min till decompression.Then the rats′survival rate was observed after 0.5 h, lungtissue specimens were collected from each rat, the pathological score was taken , according to the degree of lung injury and the R language was used for statistical analysis.Results The mortality rate was 50%.Lungtissues of these rats were pathologically characterized by stromal lung thickening, edema, and hyperemia.Kruskal non-parametric test analysis found a significant difference (P=0.0016) between the two groups .Nemenyi test was used in pairwise comparison .The death and survivalanimals in escape group compared with the control group, the scores were significantly different (P<0.05).The scores had no significant difference between the deach and survivalanimal in escape group .Conclusion Decompression sickness caused by fast floating es-cape can significantly damage the blood-lungbarrier to cause pulmonary edema .