Abstract: In order to further find the efficient insecticides for the prevention and control of the important crop pest, Frankliniella intonsa, to delay the drug resistance of Frankliniella intonsa population and improve the control effects of insecticides, the lethal effects of the three chemical insecticides (30% dinotefuran suspending agent, 14% spirotetramat·dinotefuran suspending agent, and 30% flonicamid·spirotetramat suspending agent) on the eggs and nymphs of Frankliniella intonsa were determined. The results showed that: when the pepper leaves were treated with the insecticides for 3 days or 5 days, the mortality of eggs in the treatment group of 30% flonicamid·spirotetramat suspending agent was significantly higher than that in the treatment group of 30% dinotefuran and 14% spirotetramat·dinotefuran suspending agent. There were no first-instar nymphs hatched in the treatment group of 30% flonicamid·spirotetramat suspending agent, and the hatching rate was significantly lower than that in the treatment group of 30% dinotefuran and 14% spirotetramat·dinotefuran suspending agent. On the first day after the first-instar nymphs of Frankliniella intonsa in the pepper leaves were treated with the insecticides for 5 days, the mortality rate of the first-instar nymphs in the treatment group of 30% flonicamid·spirotetramat suspending agent was 17.78%, which was significantly lower than that in the treatment groups of 30% dinotefuran (31.11%) and 14% spirotetramat·dinotefuran (31.1%). On the 2nd and 3rd day after the treatment, the cumulative mortality of the three insecticide treatment groups was significantly higher than that of the control group with clean water, but there was no significant difference among the three insecticide treatment groups. Except for the control group with clean water, all the eggs and nymphs of Frankliniella intonsa treated with the three insecticides could not develop normally or reach to the second-instar nymph stage and then die. The 30% flonicamid·spirotetramat suspending agent had the best lethal effect on the eggs of Frankliniella intonsa, while the 30% dinotefuran suspending agent and 14% spirotetramat·dinotefuran suspending agent had better lethal effect on the nymphs of Frankliniella intonsa. In this study, the lethal effects of different insecticides in the developmental stages of the eggs and nymphs of Frankliniella intonsa were clarified, in order to reduce the crop losses caused by the feeding stages of the larvae and adults of Frankliniella intonsa, and provide the technical support for the safe production of crops.