The high-temperature tube furnace was applied to simulate the rotary hearth furnace (RHF) for the direct reduction of the zinc-bearing dusts from steel plants. The soot generated in the direct reduction process was studied by chromatography, X-ray diffraction (XRD), .and scanning electron microscopy (SEM) etc. The results suggested that the main phases of the soot were ZnO, KCl, NaCl and Zn5(OH)8Cl2H2O. Furthermore, the contents of Zn reach to 64.2% which could be used as secondary resources for zinc making. It is concluded that KCl and NaCl resulted from the volatilization from the briquettes at the experimental temperature of 1573K, while the ZnO were produced by the oxidation of the Zn vapor reduced from briquettes.