Over than 5000-m thickness of marine Devonian carbonate system deposited in Guizhong Depression isa marine residual basin. The basin experienced for five main evolution stages during Devonian period. It is considered to be hydrocarbon potential in southern China. Organic reefs that developed from Early Devonian Emsian to early Late Devonian are distributed between mudstones and carbonate rocks, which plays an important role in hydrocarbon accumulation. Based on geological and geophysical data, the distribution rule of Devonian reefs is discussed. By seismic and gravity anomaly, the authors constructed the lithological stratification of the Devonian reefs, predicted the locations of paleo-platforms in the depression, and predicated zones where reef mounds are probably concentrated. 17 potential reef reservoir bodies of seismic anomaly are sited from Devonian Yintang Fm to Donggangling Fm, of which the largest one with an area of 307km2 is located between Yicheng and Datang. It is suggest that it will be the first selective one for drilling target because it is far from ancient faults and so probably has a good preservation condition of hydrocarbon.