A self-built double-pulse remote Laser-Induced Breakdown Spectroscopy system in a collinear configuration was used to investigate the magnesium alloys. The enhancement of the intensity was observed, about 4.7 times compared with single pulse LIBS. The peak intensities of line Y II 366.4 nm and Zr I 468.7 nm were used in the calibration curves, and the correlation coefficients were 0.9998 and 0.9547 respectively.