As the main form of arc energy transport, radiation plays a key role in arc interruption processes. This paper focuses on eco-friendly gas C4F7N and its mixtures with CO2 and N2. The two-dimensional (2D) magnetohydrodynamics (MHD) model is established by coupling the net emission model for gaseous arcs. Based on this model, the radiation transport characteristics of C4F7N arcs during the moving of electrodes are analyzed and the influences of currents and mixture ratios on arc shapes, temperatures and radiation energy are also investigated. The experiment platform for arc optical diagnosis is further constructed. The arc shapes and spectrum information are collected by a high-speed camera and a spectrometer respectively, which validate the simulation model. It is found that due to the distribution of arc radiation energy along the X axis, the C4F7N arcs are gourd-shaped. As the current is raised, the arc radiation energy increases, leading to a clearer gourd shape. With the increase of gas content in C4F7N, the arcs gradually shrink by the action of radial Lorentz force.