The geometric structures and electronic properties of MgSin (n = 1-10) are studying by using the B3LYP method of the density functional theory (DFT) at the 6-311G (d) set basis level. And several lower energy geometric structures of the MgSin (n = 1-10) are obtained. The results show that the lowest energy structures of the magnesium doped silicon clusters can exist stably.