Abstract: The radial spacings of the primary and pilot staged swirler is an important parameter for the lean direct injection combustor. In this paper, the particle image velocimetry technology, Mie scattering technology and particle size measurement technology were used to study the cold flow and spray characteristics under three different radial spacings of the primary and pilot stage. The experimental results show that, under normal temperature and pressure, with the increase of two-stage radial spacing, the central reflux area changes from narrower in front and wider in back to the same width in front and back, the backflow zone between the two stages keeps increasing, the fuel cone angle of the pilot stage is less affected, the main stage jet deflects gradually from the main stage to the pilot stage, and the main fuel crushing effect continues to deteriorate. When the radial spacing of the two-stage is 20 mm, the atomization effect of the main fuel is the best, and the atomization effect of the secondary fuel is also good.