Achieving carbon peaking and carbon neutrality is crucial to accelerating the construction of ecological civilization and promoting high-quality national development. Carbon dioxide as an additive in industrial combustion can effectively reduce soot production. The main background of the paper is derived from industrial flares, which are devices that convert unrecoverable combustible gasses produced in industrial production into environmentally friendly combustion products through combustion. The paper presents the effect of cross airflow on the flame characteristics and flame radiation fraction of ethylene jet fires with carbon dioxide addition. The experiments were carried out on the test bench at one end of a wind tunnel facility with size of 22 m (length) × 1.2 m (width) × 0.8 m (height). The flame geometrical features (i.e. flame length and lift-off height) and flame radiation fraction of ethylene jet fires with carbon dioxide addition under cross airflow were analyzed. It was found that the flame lift-off height of ethylene gas and carbon dioxide is a linear function with the fuel ejection velocity, which is consistent with the pure fuel phenomenon studied by previous researchers. For the same heat release rate, the flame radiation fraction decreases with the increase of the volume flow of CO2 added to ethylene. Moreover, for the given test conditions, the flame radiation fraction of ethylene jet fires with carbon dioxide addition decreases with the increase of cross airflow speeds. A model for the dimensionless flame length of ethylene jet fires with carbon dioxide addition was obtained. Finally, a new global model is also proposed to characterize the flame radiation fraction of ethylene jet fires with carbon dioxide addition by accounting for the effect of cross airflows.