Ordovician karst landforms are wide distributed in eastern Central Uplift, Ordos Basin. The accurate characterization and identification of small karst paleogrooves is important to approach hydrocarbon accumulation and improve success rate of exploration. The seismic response of paleogrooves is the depth of the grooves instead of the width of them. It is shown that as the dip angle is more than 5°, the seismic response is unclear. As the erosion depth of them is at 10 m to 5 m, seismic phase axis is reversed. As the erosion depth of them is at 30 m to 10 m, the seismic phase axis gaining even increases. As the erosion depth is greater than 30 m, the seismic displays compound waves. By this method, a group of the middle and small karst paleogrooves have been effectively identified and confirmed in the Middle array of Ordovician Majiagou 5 Submember using well data and available geologic data and post-stack migration profiles.