Caldor smelting is one of the most important methods for treating decoppering anode slime by pyrometallurgy. This research aims to solve the serious problems of poor melting performance and large precious metals loss of reduction smelting slag for treating decoppering anode slime emerged in a domestic enterprise. Therefore, the process optimization and regulation on the Na2O/SiO2 ratio of reduction smelting slag in the Caldor furnace is carried out. The thermodynamic analysis by Factsage software is employed; simultaneously, the physicochemical properties of reduction smelting slag are measured combined with the XRD analysis and Raman spectroscopy characterization. According to the liquid phase diagram and the tested physicochemical properties of the PbO-Na2O-SiO2-BaO system, appropriately increasing Na2O/SiO2 ratio can effectively decrease the melting temperature and viscosity of reduced smelting slag, without changing the slag rate and the adding amount of total flux. The structure of reduction smelting slag varies from dimer structure silicate of Si2O76- to tetrahedron structure silicate of SiO44- when the Na2O/SiO2 ratio of reduction smelting slag changes from 0.42 to 0.60. The increase of network modification of Na2O results in more bridging oxygens converting to non-bridging oxygens in the reduction of smelting slag, and the ratio of Si2O64- chain structure silicate and Si2O52- sheet structure silicate decrease also, which lead to the lower of polymerization degree of slag. The analysis results show that the Qn of bridged oxygen is consistent with the silicate structure of the smelting slag. Simultaneously, the hemispherical melting temperature of slag decreases from 1178℃ to 950℃, and the viscosity can decrease about 45.2% at a smelting temperature of 1100℃ when the Na2O/SiO2 ratio of the reduction smelting slag varies from 0.42 to 0.60. As a result, the fluidity of reduction smelting slag is improved obviously, which can verify the above change trend of slag microstructure from the view of macroscopic properties. The results prove that it is feasible to regulate the Na2O/SiO2 ratio of reduction smelting slag to lower the bridging oxygen number and polymerization degree of complex anionic, to improve the physicochemical properties.