The phospholipase A2 gene partial cDNA sequence was amplified by RT-PCR in latex. The sequence analysis displayed that it was identical with the cDNA sequence of hev b7 published by Kostyal D.A (1998). Hev b7 was similar to patatin and had phospholipase A2 gene indicated that the expression level of phospholipase A2 gene was different under various treatments. In the young tree experiment, it showed that the intensity of hybridization signal of the primary tapping was the weakest, while the intensity of hybridization signal of the first tapping with Ethrel treatment was stronger than that of the first tapping without Ethrel treatment. In the mature tree experiment, the clone Reyan7-33-97(Ethrel) was the strongest among four treatments, and the clone Reyan7-33-97 (no Ethrel) was stronger than the clone PR107(Ethrel), while the clone PR107(no Ethrel) was the weakest.