To explore the effect of temperature and salinity on the mitochondrial DNA (mtDNA) copy number of Palaemon carinicauda Holthuis, 1950, 5 temperature groups (10, 15, 20, 25 and 30°C) and 6 salinity groups (10, 15, 20, 25, 30 and 35) were set up, respectively. Subsequently, the numbers of copies of mtDNA of samples from all groups were detected by the TaqMan probe method. The results showed that the mtDNA copy number in the temperature samples was 2388, 2366, 4158, 4805 and 6027 at the above-mentioned temperature values, respectively. Obviously, the number of mtDNA copies in the cell tends to increase as temperatures rise. In addition, the mtDNA copy numbers of the salinity samples was 2609, 2593, 3215, 3478, 2618 and 2709, respectively, at the experimental salinities as listed above. This indicates, that the copy numbers of mtDNA tend to increase at first, and then again to decrease as the salinity values rise and pass beyond a threshold.