At 6-31G^*^* level ab initio calculation of quantum chemistry was used in the theoretical research on the structure and stability of the substituted disilynes and their isomers HYSi~2 and Y~2Si~2 (Y=F, Cl, Br, Li). The effect of substituents on the stability of various isomers, especially that of Si-Si bond, is discussed in detail. The results show that among various substituted disilyne isomers, disilenylidene structures and double-bridged structures have the lowest energy and can be experimentally detectable, while the classical linear structures have higher energy and are thus unstable.

Key words: AB INITIO CALCULATION, ISOMER, STABILITY