Abstract: We conducted a field experiment of releasing Trichogramma dendrolimi in poplar plantation to study the control of Notodontidae’s eggs in Populus×euramericana. The results showed that two releasing densities of T.dendrolimi had a certain function on the control of Notodontidae and increase the egg parasitization of T.dendrolimi significantly. The egg parasitization rate of Notodontidae at 40 000 rats/667 m²(60%)density of T.dendrolimi released was much higher than that at 20 000 rats /667 m²(40%)released. After T.dendrolimi released,the leaf damaged rates of 107^#,46^#,2025^# poplar varieties were decreased from 31.84%,41.23%, 29.73% to 3.01%,2.42% and 4.22%, respectively,but there were no significant differences among three poplar varieties. The eggs parasitization rate of Notodontidae increased from 10.52%,8.86%, 9.36%to 69.41%, 45.54% and 70.7% for three poplar varieties after T.dendrolimi released, respectively, and there were no significant differences among the three poplar varieties. The effect of a mixed release of T.dendrolimi and Chouioia cunea Yang mixed on controlling Notodontidae was significantly better than only releasing T.dendrolimior or C.cunea Yang.