The invention, belonging to a synergistic insecticidal composition, discloses an insecticidal composition comprising a compound (A) indoxacarb and a compound (B) etofenprox. By mixing with proper proportion and using processing technologies of modern pesticide preparations, the insecticidal composition can be prepared into missible oil, suspending agent, wettable powder, water dispersible granules and other conventional pesticide formulations for controlling insects on cotton, fruit tree, vegetable, potato, paddy rice and other crops. The weight ratio of the compound (A) indoxacarb to the compound (B) etofenprox is 1 to 1-50. The insecticidal composition has high insecticidal efficiency, can effectively control the insects on cotton, fruit tree, vegetable, potato, paddy rice and other crops. The control effect of the insecticidal composition is obviously higher than the single used compound (A) or the compound (B), and the dosage of each active substance is greatly reduced. The invention has an ecological significance and an important environmental significance.