The common pistachio psylla, Agonoscena pistaciae Burckhardt & Lauterer (Hemiptera: Psyllidae) is one the most important insect pests of pistachio trees, Pistacia vera L., in Iran due to significantly reducing the quantity and quality of the pistachio product. As its damage is severe and economic, farmers apply different kinds of insecticides to control A. pistaciae. However, the optimal timing of insecticide application is crucial to achieve a successful pest control program. In this study, the efficacy of five chemical compounds including Abamectin (Vertimec® EC 1.8%), Acetamiprid (Mospilan® SP 20%), Hexaflumuron (Consult® EC 10%), Hexaflumuron (Consult® EC 10%) + Abamectin (Vertimec® EC 1.8%), and Thiamethoxam (Memory® SC 24%) were investigated against nymphs of pistachio psylla at concentrations of 0.6 ml/L, 0.25 g/L, 0.7 ml/L, 0.5 +0.3 ml/L, and 0.4 ml/L, respectively, under field conditions. The experiment was conducted at a pistachio orchard, Ahmadaghaei variety, in Rahimabad village, Isfahan province, Iran. The chemical application was conducted at two separate times in the middle May (early control) and late June (late control) of 2022. The number of A. pistaciae nymphs was recorded one day before and 3, 7, 14, and 21 days after spraying. The data were computed to percentage efficiency using Henderson-Tilton equation. The results showed that the mean percentage efficiency of the five mentioned insecticides in the early control treatments at 3, 7, 14, and 21 days after application was evaluated 54.89, 43.06, 40.59, and 22.78%, 83.60, 78.82, 55.15, and 38.24%, 76.24, 82.63, 65.31, and 51.10%, 81.20, 79.72, 60.35, and 41.28%, and 90.97, 84.85, 75.44, and 59.97%, respectively. However, the estimated parameter of the insecticides in the late control for the mentioned days was calculated 33.27, 30.68, 23.18, and 19.12%, 49.62, 54.28, 35.16, and 24.28%, 40.53, 49.48, 38.85, and 28.19%, 45.84, 40.59, 33.22, and 25.83%, and 58.72, 61.42, 50.23, and 32.08%, respectiv