For the first time thermodynamic modeling was used to development of an analysis technique of ferrotungsten by ICP-AES. Using the simulation three methods of sample preparation for ferrotungsten analysis were considered including dissolution using an acids mixture and two variants of fusion, the effect of alkali metal on tungsten emission was studied, the efficiency of internal standardization for reducing errors from spectrometer operating parameters fluctuation was shown. Optimal spectral line for determination of tungsten, internal standard and its spectral line were selected. Lacking for modeling thermochemical properties of some tungsten complexes in the crystalline state and in solution were calculated using the group contributions method. Theoretically grounded scheme of express ICP-AES tungsten determination in ferrotungsten was developed. Its experimental testing on certified reference materials showed a significant decrease in the error of analysis results using Sc II 424.683 nm as an internal standard. The proposed technique provides the requirements for results accuracy similar ones of gravimetric methods.