Doping Si atoms into crown ethers has the potential to greatly enhance their complexation ability to metal ions, but the regulation mechanism is still unclear. 12-Crown-4, 1,1-demethyl-1-sila-12-crown-4, 1,1,2,2-tetramethyl-1,2-disila-12-crown-4, 1,1,2,2,4,4,5,5-octamethyl-1,2,4,5-tetrasila-12-crown-4 and 1,1,2,2,7,7,8,8-octamethyl-1,2,7,8-tetrasila-12-crown-4 were selected as the models and the interactions between crown ethers and Li+ were deeply studied by quantum chemical density functional theory calculations. The results show that due to the increase of the O—Li+ coordination bond length, the covalent interactions of the 12-crown-4 with two or four Si atoms are slightly weaker, but the electrostatic interactions and dispersion interactions are stronger, and the Pauli repulsions are smaller, which ultimately lead to the stronger interaction between all the Si hetero12-crown-4 and Li+ than 12-crown-4. The above mentioned favorable factors stem from the fact that the electrons of the weakly electronegative Si in the Si—O bond are significantly polarized toward O, which enhances the advantage of O's negative electrostatic potential. Meanwhile, the complexion of Si hetero12-crown-4 with Li+ causes the —SiMe2—SiMe2— or —CH2—SiMe2— units to be away from Li+, effectively avoiding the Coulombic repulsion between Si—Li+. The crown ether-Li+ interaction mechanism revealed in this work will provide theoretical guidance for the future designing and synthesizing of heteroatom crown ethers with efficient extraction capabilities.