The M-T curves， M-H curves, infrared spectra, Raman spectra，ρ-T curves and MR -T curves of La0.7-xGdxSr0.3MnO3 (x= 0.00, 0.10, 0.15, 0.20, 0.30 , 0.40, 0.50, 0.60, and 0.70) are studied. The experimental results indicate tha t with increasing Gd doping, the system undergoes a transition from long-range f erromagnetic order to the cluster-spin glass state and further to an antiferroma gnetic order. With heavily doping content, the transport property exhibits an ab normal behavior under magnetic background. The variation in magnetic structure a nd extra magnetic coupling caused by Gd doping lead to colossal magnetoresista nce.