The paper primarily studied the geological background of organic rich shale and its distribution characteristics, reservoir forming conditions and potential favorable areas of shale gas reservoir development. The study started from basic data such as the field surface outcrops, underground core and laboratory test results, and by the analysis of the accumulation conditions of shale gas in Northwest Guizhou, and using comprehensive information method, the favorable areas were predicted. The results indicate that the organic rich shale is at the bottom of the Upper Ordovician Longmaxi Formation and Lower Silurian Wufeng Formation. The organic rich shale in the study area were characterized by wide distribution，great thickness, good organic type, high organic content，high organic thermal evolution degree and high hydrocarbon potentials. The shale is rich in brittle minerals, with great quantity of matrix micropore and cracks, and good reservoir conditions, which offered sufficient accumulated space and migration pathway for shale gas. The result of well site desorption test showed that the black shale all have high performance of gas adsorption. In a word, the tectonic evolution characteristics and geological conditions in this area are similar to the typical shale gas basins in America，and the study area is a favorable and prospective place for shale gas exploration，having lots of advantages for forming shale gas reservoir.