The concentration response curves were calculated based on pulse tracer input technique by means of CFD method adopted RANS equations and renormalization group k-ε turbulence model. The characteristic of residence time distribution measured at different outlet with different inlet velocities and aspect ratios were ealeulated and analyzed by orthogonal experiment, and the orders of factors were ranked by the range analysis of mean value and square deviation. The results show that the order of axial back mixing coefficient is 10 ^-2, and the flowing state of the fluid in the kenics static mixer approaches plug flows. The mean residence time decreases with increasing flow rate of the fluid and increases with the increasing length and aspect ratio of the static mixers.