Abstract: It is in line with the requirements of agricultural sustainable development to find safe solvents to replace toxic solvents in pesticide formulations. The substitution of harmful solvents in EC has been quite effective, and the substitution of harmful solvents in the microencapsulated formulation should have been given much attention. The effects of methyl oleate and 150# solvent oil on the stability of the oil phase were evaluated to select the type and amount of solvent, then the release performance, anti-photodegradation performance and field application effect of 9% pyraclostrobin microcapsule suspension were investigated in this work. The results showed that when methyl oleate was used as a solvent and the mass ratio of technical material to solvent was 1 : 2, the microcapsules were spherical with an average particle size of 2.92 μm. Compared with the microcapsules with 150# solvent oil as solvent, the cumulative release rate of microcapsules with methyl oleate as solvent was 92% at 20 min, while that of microcapsules with 150# solvent oil was only 50%. Under the simulated UV light intensity, the content of pyraclostrobin in the microcapsule with methyl oleate as solvent was 30.59% higher than that in the microcapsule with 150# solvent oil as solvent at 100 min. The results of the field efficacy test showed that the control efficacy of 9% pyraclostrobin microcapsule suspension with methyl oleate as solvent was 16.59% and 29.34% on 32^nd day after application, respectively, which were higher than that of 9% pyraclostrobin microcapsule suspension and pyraclostrobin EC with 150# solvent oil as solvent. The above results suggested that the solvent has an effect on the stability and application performance of pesticide microcapsules, and the formula should be further optimized, which provides a theoretical basis for the fine processing of pesticide microcapsules.