Nano powders have wide range of applications and different methods are available for production. In the paper the three methods discussed are mainly used in pharmaceutical industries and electronic industries for the production of nano powder. If we compare the two processes (PGSS) and (DELOS) Process there is difference between the shapes of the powder in (PGSS) Powder is spherical and in (DELOS) there are cylindrical and dendrite. The powder produced in (PGSS) is in amorphous form where has in (DELOS) it is crystalline form. In the above methods (PGSS) process is more advantageous than any other process because it is flexible as we can control the size of the powder produced by controlling the amount of super critical fluid used in the process and we can maximize and minimize the yield of the production.