In metallurgical dusts treating by RHF (rotary hearth furnace) direct reduction, processes of Zn, K, Na removal and flue gas formation have significantly influence on RHF process. Direct reduction experiment on cold bonded briquettes, made by mixing metallurgical zinc-bearing dusts with proper proportions, are investigated in a high temperature tube furnace simulated RHF. Ingredients, microstructures and phase compositions of flue gas and secondary dust are collected and analyzed. The results show that removal rates of Zn, K, Na and Pb are 98%, 80%, 88% and 85% respectively, gas ingredient of flue gas of N2, CO, CO2 are 71.4%，14.5% and 14.1% respectively, and phase compositions of secondary dust are ZnO, KCl, Zn5(OH)8Cl2H2O, PbO and NaCl. Studies show that ZnO content of secondary dust is up to 80%, which can be reused as secondary zinc resource. Then mechanism of removal of Zn, Pb, K and Na and forming of flue gas are analyzed in direct reduction process.