Abstract: The structure， flowfield distribution and the dust separating procedures of innerspeeding vortex cyclone collector are very different from that of traditional cyclone dust collectors． The separation areas are divided into outer vortex area, inner vortex area, mixing vortex area and central vortex area. The mixing vortex area and the central vortex area are important factors for inner speeding vortex cyclone dust collector. This paper investigated the flowfield distribution in mixing vortex area and in central vortex area．The airflow velocity was calculated, and the three dimension vector of the flowfield distribution was obtained. The test results showed that:1) the tangent velocity distribution of mixing area is quasifree vortex, and the index of quasifree vortex is 0.5,the tangent velocity is higher than that of other areas with the action of inner speeding vortex,and the maximum tangent velocity is 22.6m/s which is helpful to the dust separating;　2)　the axes velocity distribution in mixing area is parabola form and increases along the radial direction,the maximum axes velocity is 1.51m/s,and the radial velocity in mixing area is centripetal direction;　3)　in central vortex area, the tangent vortex distribution is coerce vortex, the highest axes velocity is about 40m/s in average and the radial velocity is very small and centrifugal.