Viscosity coefficient is the resistance to the liquid, the definition is the need of the shear force when the flow speed is 1c㎡, called MPAa-s,the unit is Pas. The viscosity is a attribute of the liquid. When the liquid flow in the pipe, it has three states of laminar flow, transitional flow, and torrent. So do the mixing. The most important parameter which decides the states is viscosity. During the procedure of mixing, it is stated that the viscosity lower than 5Pas is low-viscosity liquid. For example, water, sucrose, jam, Honey etc.. Mid-viscosity is 5-50Pas, for example, printing ink, toothpaste etc. High-viscosity is 50-500Pas, for example, gum, growth rate of sol, organic silicon. For the low viscosity material, the minor diameter mixer can drive liquid, but for the high viscosity material need the blender to push. Impeller which applies to the low-viscosity and mid-viscosity material is paddle agitator, open turbine agitator, push type, Burma Gold Type, etc. The viscosity may change during the reaction, that need the impeller which can need the demand of the high viscosity, for example, Pan can impeller.