This paper focuses on investigating the characteristic modes and structures in non-premixed swirling methane/air flames. Using the Particle Image Velocimetry (PIV) technique, the experiment measured the velocity distributions of the swirling flame. Cold flow conditions have been included to provide a picture of the flow field and to demonstrate the modifications induced by combustion. The characteristic lengths, velocity vectors, streamlines, and velocity distributions are presented and discussed. The experiment shows that a large spatial separation at the exit between the central and swirling annular jets can expedite the formation of a recirculation zone. Complex flow structures are found in the recirculation zone. Moreover, the differences between cold swirling flow field and combustion swirling flow are analyzed at length. The data from this experiment is helpful for optimization of the non-premixed burner design, and can be established as benchmarks for the development and validation of combustion numerical simulations.