A 2D temperature field scanning measurement method in a combustion flow based on Coherent Anti-stokes Raman Scattering (CARS) was explored for temperature distribution measurements. By synchronized scanning incidence lasers and exit CARS signals, the temperatures of discrete points for methane/air premixed flame in a horizontal section were measured and a 2D temperature field was reconstructed by using 2D linear interpolation. The temperatures of the flame in the same space position in scanning processing was measured with synchronizing scanning method, by which the additional effect of flame space distribution in homogeneity on scanning measuring temperature was removed. Finally, the measuring uncertainty of the scanning CARS system was analyzed in a given experimental state. The experimental results for scanning measuring the same space position show the average temperature in the point is 2 074 K, meanwhile, the measuring uncertainty of the scanning CARS system is accounted below 21 K at the same experimental condition. In conclusion, the research quantizes the measuring uncertainty of the scanning CARS system, improves the reliability of results of scanning temperature measurement and provides an experimental foundation for the high precision measurement of flame temperature distribution, simulation validation of Computational Fluid Dynamics(CFD) and the investigation of flame problems.