This paper focuses on investigating the flow structures in a multi-hole swirl burner. Using the Particle Image Velocimetry(PIV) technique, the experiment measured the velocity distributions of the swirling flame in a muti-hole burner. The experiments show that there is a central recirculation zone (CRZ) in the middle of the flow field, and two counter-rotating vortices exist along the centerline symmetrically. With fuel jet increase: the width of recirculating zone and axial mean velocity peaks changes little; length of recirculation zone and the biggest reverse flow velocity increases; the expansion angle of swirling jet increase at first, and then changes little; axial non-uniform coefficient of outlet reduces at first, and then increases. With airflow velocity increase: axial mean velocity peaks increase; the dimension of recirculating zone and the expansion angle of swirling jet are unchanged; axial non-uniform coefficient of outlet increases.The data from this experiment is helpful for optimization of the swirl burner design, and can be established as benchmarks for the development and validation of swirl combustion numerical simulations.