Abstract:This paper reports the chemical constituents resistant to Bactocera horsfieldi in different kinds of Populas deltoides. We discovered that the resistance of Popular deltoides was not related to nutritious substance but related to phenol componemts and tannin, 31 phenol constituents .were determined by GS/MS/DS. A few constituents are discovered in Populas deltoides. At times, 13constituents are also determined by HPLC.