© 2020, Springer Nature B.V. Lead (Pb) perovskites can be synthetically modified to form colloidal nanocrystals which exhibit remarkable optoelectronic properties in the various fields such as light-emitting devices, flexible electronics, and photodetectors. However, because of the toxicity issue of Pb, nanocrystals of Pb free such as tin (Sn)-based perovskites have got attention. In the present work, we have selected the Sn-based perovskite, Cs2SnI6, owing to the high air and thermal stability. Quantum dots of Cs2SnI6 were prepared by using two methods, namely the hot-injection method and the ultrasonic irradiation method. The difference between Cs2SnI6 particles generated by these two methods was discussed. The particles synthesized by using the hot-injection method were less than 10 nm in size and were aggregated structure due to particle tight-binding energy. On the other hand, the particles by using the ultrasonic irradiation method gave a mono-dispersed solution. The particle size was from several ten nanometers to several hundred nanometers.