Using core, rock thin section, cast thin section, scanning electron microscope and X diffraction analysis data, combined with previous research results, we studied the petrological characteristics of long 6 sandstone reservoir in Longdong area of Ordos Basin. And the petrological characteristics of different blocks were compared and analyzed. The results show that the main rock types of this area are lithic feldspathic sandstones and feldspar sandstones. Quartz, feldspar content is high, detritus, interstitial material content and compositional maturity are low. The interstitial material is mainly of metamorphic detritus, and the plastic detritus content is high. The change of relative content of rigid-plastic debris has obvious orientation; Sorting is medium-well, particle is main of sep-angular, structure maturity is relatively high. Petrological characteristics of each cell block are different. The difference of provenance and sedimentary environment is the important factor for the petrologic characteristics.