Objective：To select stable expression of reference gene and to explore the water channel protein 5 mRNA expression for drowning rat model in different time points. Methods：Drowning rat was modeled in different time points（0 min，n=6；15 min，n=6；4 h，n=6；16 h，n=6；48 h，n=6；72 h，n=6）. Total RNA was extracted from samples and reversed transcription was conducted for cDNA syn－thesis. Candidate reference genes were detected by real-time PCR. In order to screen out the most stable reference gene，geNorm and NormFinder was used to rank the expression of each gene. Then，AQP-5 mRNA expression was detected by qRT-PCR. Results：ACTB was the most stable reference gene. Our study showed that the expression of AQP-5 mRNA was downloaded except 72 h in this model（15 min/0 min=0.51，P<0.001；4 h/0 min=0.53，P<0.001；16 h/0 min=0.63，P<0.001；48 h/0 min=0.81，P<0.05；72 h/0 min=0.89，P>0.05）. Conclusion：AQP-5 mRNA expression has some positive meaning and improves forensic identification in drowning model.