The outlet flow fields of the double-stage swirler with different Venturi length are measured with particle image velocimetry (PIV) and the effect of Venturi length on outlet flow fields is investigated and discussed. The downstream flow field characteristics of swirler are displayed, and the distributions of axial velocity and radial velocity are gained. The results indicated that the radial movement of Vortex core away from center line results in the increase of radial distance from 22.2 mm, to 29.2 mm, and the area of central circulation zone becomes larger with the increase of Venturi length. The characteristics of axial velocity and radial velocity are in favour of combustion organization.