Nanoparticles have been used in various fields, such as electronic materials, pharmaceuticals, and cosmetics. Therefore, it is necessary to generate nanoparticles with a uniform particle size appropriate for each purpose. In previous studies, nanoparticles were generated by quenching microdroplets for recrystallization using microfluidic droplet generation devices and quenching devices. However, although the temperature of the solution is important for generating nanoparticles by recrystallization phenomenon, the liquid temperature was not maintained during droplet generation. In this study, the liquid temperature at the droplet generation process has been maintained and a nanoparticle generation system has been constructed. The structure of the quenching device is also modified to improve the cooling effect. As a result, nanoparticles with small diameters have been generated.