Abstract: The electronic structures of O-isopropyl-N-propyl thionocarbamate (IPP) and O-isopropyl-N-ethyl thionocarbamate (Z-200) were calculated by density functional theory. In combination with Klopman's generalized perturbation theory, the collecting performance of the new thionocarbamate IPP was predicted. The results showed that the energy of the highest occupied molecular orbital (E_HOMO) and the energy of the lowest unoccupied molecular orbital (E_LUMO) of IPP were higher than those of Z-200, and the electronegativity was lower than that of Z-200. It could be predicted that the collecting ability of the new thionocarbamate IPP was stronger than that of Z-200, and the selectivity was weaker than that of Z-200. Then, the target molecules were synthesized and characterized by nuclear magnetic resonance spectroscopy (NMR). The flotation tests of pure minerals and actual ore were conducted, and the results were in good agreement with the preliminary prediction. The results showed that when the hydrocarbon group attached to the N atom in the molecule is replaced by a propyl group, the E_HOMO and E_LUMO increase, and the molecule has a strong collection ability and weak selectivity. The frontier orbital properties such as the energy can be used to predict the flotation performance of thionocarbamate.