Abstract: Objective To explore the changes of secretory phospholipase A2 mRNA (sPLA2) expression in rats lung tissue after extremely fast decompression. Methods Rats treated with extremely fast decompression, were detected the expression of sPLA2 mRNA in rats lung 8 times from 0 to 210 rain,and the interval was 30 min. At the same time, the pathological changes of rats lung and the lung wet/dry ratio were observed. Results Thirty rain after the rats were treated the expression of sPLA2 mRNA in rats lung got an obvious peak. The pathological character of the lung injury experienced a repeated course from serious to slight and gradually aggravating again. The lung wet/dry mass ratio experienced a repeated course from large to small.Conclusions In 210 minutes after extremely fast decompression, the degree of rats lung injury experienced a course from serious to slight, then gradually aggravating again. The level of sPLA2 mRNA in a rats lung tissue treated with extremely fast decompression was from low to high, then stepped down again. This mechanism needs a further study.