This paper mainly introduces the principle and characteristics of laser particle size analyzer and applies it to study the influence of different composition on the particle size distribution during the formulation development process. At the same time, the influence of different production process parameters on the particle size distribution during the production process of the preparation is investigated. The research results show that the laser particle size analyzer can not only optimize the component content in the formulation development, but also effectively monitor the particle size distribution of the pesticide in the process production to ensure the stability of product performance.