Reduction of NO by biogas without tar and with tar was investigated. Flow reaction experiments were performed at high-temperature (>= 1000 degrees C), and the main parameters, such as initial oxygen concentration, bulk equivalence ratio, temperature, and initial tar content, were studied. The simulated biogas was prepared by mixing CO, CH4, H-2, and CO2, and toluene was selected as a model compound as the biomass gasification tar. The moderate fuel-rich environment is favored to a high level of NO reduction by both biogas without tar and biogas with tar. The optimal bulk equivalence ratio, phi, for NO reduction by biogas with tar is larger than that of NO reduction by biogas without tar. The effect of temperature on NO reduction by biogas with model compound is stronger than that by biogas without tar. The comparison of NO reduction by biogas without tar and biogas with tar indicates that tar can either promote or limit NO reduction by biogas. The experimental results here will be helpful to the further investigation of NO reburning.