The advantages of suspension concentrate and the process of 40% chlorothalonil·pyrimethanil suspension concentrate were introduced. Through the selection of additives, test of the indicators, the optimum formulation of 40% chlorothalonil·pyrimethanil suspension concentrate was determined, the suspension rate of the optimum formulation was above 90%, the average particle size was below 3μm, the stability was qualified, the index were in accordance with the technical standard of suspension concentrate.
