To solve the problem of high NO x emission of 600-MWe boilers in power plants, we established a cold gas-solid modeling testbed scaled by 1:5 for twochannel overfire air (OFA). A phase-Doppler anemometer was used to measure the characteristics of the outlet flow field of the two-channel OFA under different OFA rates. We also verified the industrial feasibility of this testbed under loads of 300 and 600 MWe. The influence of the OFA rate on the divergence angle of the outlet jet was small: When the OFA rate was increased from 15% to 35%, the divergence angle only increased by 2.2 . The attenuation