The emission spectra from the plasma produced by using Nd:YAG laser to ablate the solid Mg sample was measured with an optical multichannel analyzer. The Stark broadening of Mg 552.84, 516.74, 470.30 and 383.83 nm lines were obtained for a delaying of 1 to 2 us time. The Shark broadening of above lines for Td=1 μs and 2 μs were theoretically calculated with the semiclassical method and electric dipole approximation. The calculatedl results consisted with the experimental ones very well.