[Objectives]  In order to control the Lissorhoptrus oryzophilus, efficaciously. [Methods]  The tests on the damage and economic threshold of rice, was carried out by envelop modifying the density of L. oryzophilus. [Results]  Infected rate of rice leaves, larval density, tillering number and single yield difference was significant, spike number, grains per spike and 1 000-grain weight had not significant difference, regression equations among the loss rate of yield and infected rate of leaves were established, after rice transplanting 5 days, 10 days, 15 days, 20 days, the economic threshold for infected rate of rice leaves were 59.65%、52.97%、50.96%、48.52%. Regression equations among the loss rate of yield and the adult density and among the loss rate of yield and the larval density were established, the economic threshold for the adult were 20 adult per square meter, the economic threshold for the larval were 130 larval per square meter. [Conclusion]  This results has important guiding meaning to prediction and prevention of Guizhou.