Abstract: Turbulent flame structure represents the species, velocity and temperature field in the turbulent combustion, which reflects the interaction between the turbulence and the combustion. It is also important for combustion model validation. The conventional PDF of curvature method can not accurately reflect the folded regions in the turbulent flame, while the network topology analysis can demonstrate these regions as it can mark the key nodes or structure in a system. In this paper, the network structure of the turbulent premixed Bunsen flame is constructed to trace the folded regions in turbulent flames. Results show that the folded regions can be traced by network structure. These regions are mainly caused by DL instability in weak turbulence, while they are mainly affected by turbulence vortex wrinkling as turbulence intensity increases. The influence of DL instability on turbulent premixed Bunsen flames is constrained by flame development. At the bottom of Bunsen flame, the DL instability does not wrinkle the flame. As the flame propagates to the downstream, the flame becomes more wrinkled due to DL instability.