Fluid viscosity is a very important factor for fluid dispensing, and it has important effect on the volume and velocity of the fluid that jetting from the nozzle outlet. This paper analyses the force that the fluid gives to needle both with low and high viscosity situation and establishes formulas. This paper compared the equivalent velocity based on fluid kinetic energy cumulative volume and fluid mean flow velocity on the condition of low viscosity and high viscosity and through comparison draws out the influence that the fluid viscosity affects on the fluid dispensing. The results well reflect the influence of the fluid viscosity effecting on fluid dispensing, and also show that the needle has long run duration in the same displacement when the fluid viscosity is high. On the high viscosity conditions, the cumulative volume and fluid mean flow velocity is less than the low viscosity situation accordingly, but their accretion process is coincident.