Polycrystal samples of La1-xSrxMnO3 (x=0.2, 0.3) have been synthesized using a sol-gel method. The effect of sintering process on the sample microstructure and Sr doping on the magnetoresistance for La1-xSrxMnO3 have been investigated. The results show that the increase of sintering temperature and time can promote the crystallization of samples and reduce the content of impurity. The additive of Sr makes Mn ion in materials relatively compact, and this causes the distorted deformation of the materials structure. The magnetoresistance (MR) changes with the Sr doping. When x=0.2, the maximum MR% of sample is about 43% and keep about 40% between 10~150K. At room temperature, the MR% will decrease to about 6.5%. When x=0.3, the order magnetoresistance (OMR) effect occures above the room temperature.