The mechanisms of lean combustion of propane with/without CO addition on a V-shaped burner have been investigated through the analysis of both flow and combustion fields. The flame patterns and flame temperatures under different mixing conditions were measured and recorded. Moreover, the measurement of chemiluminescence and the flow visualization were applied to obtain the distributions of C2* and CH* intensity, and flow velocity, respectively, during the combustion process. Also, the exhaust gas was analyzed in order to identify the participation of CO in the combustion taking place on the V-shaped burner. The flame patterns observed in this work could be divided into two groups, M-typed and hill-typed flames. The empirical results showed that the flame propagation speed increased with CO concentration in the fuel, and the addition of CO might cause a change of the flame pattern from hill-type to M-type. Besides, both the flame temperature and the intensity of chemiluminescence increased, and the lower flammability limit decreased when CO concentration in the fuel rose. By analyzing the chemiluminescence and the exhaust gas, the imping effect caused by the V-shaped burner was found improving the combustion of mixtures of Propane/CO due to the high temperature in the impinging area. In the M-typed flame, the collision of gas jets reduced heat loss, and hence the impinging flow structure was able to maintain a high temperature, so that the combustion of CO, whose activation energy is comparatively high, can still take place in the impinging area. The findings provide industries a good concept of burning CO, and it can be further extended to the combustion of syngas.