This study aims to develop the optimal formulation of spirotetramat and dinotefuran 20%SC.The surfactants such as wetting dispersant,stabilizer,thickener,antifreeze and defoamer were screened by wet sanding method.Finally,the optimal formula was obtained:spirotetramat 10%(fold),dinotefuran 10%(fold),G5000 1%,4913 2%,T-453%,S66 20%,defoaming agent 630 0.5%,glycerin 5%,magnesium aluminum silicate 0.5%,xanthan gum 0.2%,water supplement to 100%.All the measured indexes are in line with the national standard of suspension agent.At the same time,the field control effect of scale insects is outstanding.