Abundant petroleum resources are present in Ordovician Majiagou weathering-crust reservoirs in Daniudi Gas Field, Ordos Basin. Based on the analysis of core observation, thin section identification, reservoir property characters and logging data from the reservoirs, it is indicated that Majiagou reservoirs belong to tight ones with low porosity and low permeability. The reservoirs can be classified into the dissolved porosity reservoirs (in majority), the dissolved and fractured/vuggy ones and the fractured ones (in minority) in turn. In longitudinal, developing reservoir beds are Majiagou Ma1, Ma2, Ma4 and Ma5 members. Good reservoirs that distribute in plane are predicted for further exploration targets.