Abstract: In order to understand the surface wettability of leaves of different crops and improve the efficiency of chemical control by the scientific selection of adjuvants, the surface free energy and its components of wheat, corn, pepper, soybean, and apple leaves were measured by optical video contact angle measuring instrument. The contact angles of 2% femamectin benzoate ME and 20% abamectin + monosultap ME on the leaves of the above five crops were measured. The results showed that there were great differences in the adaxial and abaxial surface free energy of five crop leaves. The maximum and minimum surface free energy were pepper leaves (54.12 and 45.08 mJ/m²) and wheat leaves (3.76 and 6.42 mJ/m²), respectively. There were differences in surface free energy of the adaxial and abaxial leaves of the same crop. The adaxial and abaxial free energy of pepper leaves and the adaxial free energy of soybean leaves are dominated by polarity component, manifesting hydrophilicity, while the adaxial and abaxial free energy of wheat, corn, apple, and the abaxial free energy of soybean leaves are dominated by dispersion component, manifesting hydrophobicity. When Silwet 408 and GY-Spry were added to the 5000-fold solution of 2% femamectin benzoate ME and 750-fold solution of 20% abamectin + monosultap ME, the contact angle of the solution on the leaves of five crops decreased to varying levels. After adding Silwet 408, the contact angles of the two solutions decreased by 82.63%-100% and 85.07%-100% respectively. With the addition of GY-Spry, they decreased by 0-57.54% and 10.96%-59.13% respectively. The addition of Silwet 408 decreased the contact angle more significantly than GY-Spry. The decreasing trend of contact angle of the two insecticides added with adjuvants on the leaf surface of five crops was the same, and the decreasing trend of contact angle in 0-30 s was significantly higher than that in 30-60 s. Both Silwet 408 and GY-Spry improve the wettability of 2% femamectin benzoate ME and 20% abamectin + monosultap ME to five targets, and Silwet 408 is superior to GY-Spry.