To investigate the effects of aqueous extracts of the Achnatherum inebrians on contact activity and population growth of the pea aphid Acyrthosiphon pisum (Harris). And the method of leaf dipping with insect was compared the effects of the endophyte-infected (E+) and endophyte-free (E-) of aqueous extracts of the Achnatherum inebrians at different growth periods on the contact activity, life table parameters and population growth of the pea aphid Acyrthosiphon pisum. After the contact activity on the pea aphid of measure the mortality rate, idiophase, average fecundity, reproductive and life table parameters. The results showed that there was the E+ aqueous extract from different growth stages had significant effects on the indexes of pea aphid. At the seedling stage, the adjusted mortality of pea aphid treated by aqueous extracts of E+ was the highest, the fecundity was the lowest, the intrinsic growth rate (r_m=0.145 day^-1) and net reproductive rate (R₀=4.802 offspring) were the minimum values for those. At the maturity, the adjusted mortality rates for 24 h, 48 h and 72 h of the pea aphid treated by aqueous extracts of E+ were 26.15%, 19.01% and 9.07%, respectively. The idiophase (3.87 day), the average fecundity (8.80 offspring), reproductive rate (1.40%), the intrinsic growth rate (r_m=0.208 day^-1) and net reproductive rate (R₀=8.820 offspring) were middle values for those. In the yellow stage, the adjusted mortality rate of the pea aphid treated by aqueous extracts of E+ was the lowest and the fecundity was the strongest; the intrinsic growth rate (r_m=0.247 day^-1) and net reproductive rate (R₀=13.647 offspring) were the maximum values for those. The contact activity of the E- aqueous extracts from the Achnatherum inebrians in different growth periods had no significant effect on the population reproduction of the contemporary pea aphid, which was not different from control (P>0.05) at different growth periods. Overall, the seedling stage of the E+ aqueous extracts of the Achnatherum inebrians showed the contact activity good effect on pea aphid, with the highest adjusted mortality, and the contemporary fecundity is weakened after contact activity, and the population expansion time is prolonged, which is not conducive to its population reproduction and growth. Therefore, the results of E+ aqueous extracts of the Achnatherum inebrians at seedling stage showed a highly promising insecticidal potential, and the relatively simple and low prices of present selected method will provide theoretical basis for the research and development of new green pesticides with high effect and low toxicity in future.