Abstract: the past sixty years, most of the studies about semiconductors focused on the elementary, binary and ternary semiconductors. Recently in searching for cheap, environmentally-friendly and high-efficiency solar cell absorbers, quaternary chalcogenides I2-II-IV-VI4, such as Cu2ZnSnS4, have drawn more and more attention, and their potential application as different functional materials are being explored. However, their fundamental material properties have not been well studied. In this paper, after giving a simple introduction to the history and application of I2-II-IV-VI4 semiconductors, we will review our first-principles calculation study on these semiconductors, which includes, (i) revealed the general rules in the change of crystal and electronic structure as the number of elements increases from 2 to 4, and found clear chemical trends in their dependence on the composition elements,(ii) discussed the possible confusion in the previous structure characterization and band gap measurement, (iii) studied the phase stability of the representative compound Cu2ZnSnS4 relative to the competitive binary and ternary compounds, as well as the properties of its intrinsic defects. We believe the results presented in this paper will offer some hints for the future study of the series of I2-II-IV-VI4 semiconductors.