Abstract: The oil and gas investigations of the secondary turn laid emphasis on the Paleozoic of northern Ordos basin have finally gained important achievements after undergoing persistent effort over ten odd years,discovered successively a batch of large middle scale natural gas fields,formed a new important replaceable region in our country's oil and gas development strategy. This thesis introduces specially some actual application of geomechanics to study fields of looking for oil and gas in Early Paleozoic carbonate rock.The geomechanics based analysises on ancient tectonic system,ancient sedimentary system,ancient landforms system formed by karst,ancient bearing oil and gas system,insisted on the basic standpoints that oil and gas was controlled by tectonic system,pointed out immense resource potentiality for producing oil and gas in the basin's Lower Paleozoic and conditions of forming large middle scale gas gathering zone,and exploration direction.The exploration thinking of the prototype basin played an important role in guiding exploration arrangement and gas field discovery.