High-quality c-axis-oriented La2/3Sr1/3MnO3−δ (LSMO) films have been grown directly on Si(001) wafers by DC-magnetron sputtering without prechemical treatment of the substrate surface. The highly-oriented films have flat surface morphology and bean-like grains on the surface. It is suggested that self-assembly growth may be the intrinsic growth mechanism of these c-axis-oriented LSMO films on Si. The magnetic and electrical transport properties are measured and it is found that there exists a large low-field magnetoresistance (LFMR) over a wide temperature range down to 5 K, which is attributed to spin-dependent scattering at grain boundaries in the films.