Magnetic and electrical transport properties of the La 0.67 Ca 0.33 Mn1–x O3 (x=0-0.16),which were prepared by the sol-gel method followed by sintering treatment at 1 450,1 100 and 900℃,respectively, were investigated.Experimental results show that,with the increase of x,the resistivity of samples increases and the insulator-metal transition temperature shifts towards lower temperature.Meanwhile,the intrinsic megnetoresistance effect is weakened and the extrinsic magnetoresistance is enhanced.For the samples with x=0.16 and 0.10 sintered at 1 100℃and 900℃,respectively,low field magnetoresistance as high as about 50%can be observed.Furthermore,for the samples sintered at 1 100℃and 900℃,the grain size is not only controlled by about sintering temperature,but also by the absence of Mn content x. Magnetic and electrical transport properties of the La 0.67 Ca 0.33 Mn1-x O3 (x = 0-0.16), which were prepared by the sol-gel method followed by sintering treatment at 1 450, 100 and 900 ° C., respectively, were investigated . Experimental results show that with the increase of x, the resistivity of samples increases and the insulator-metal transition temperature shifts towards lower temperature. Meanwhile, the intrinsic megnetoresistance effect is weakened and the extrinsic magnetoresistance is enhanced. For the samples with x = 0.16 and 0.10 sintered at 100 ° C and 900 ° C, respectively, low field magnetoresistance as high as about 50% can be observed. Ferrthermore, for the samples sintered at 100 ° C and 900 ° C, the grain size is not only controlled by about sintering temperature, but also by absence of Mn content x.