The Nanpu Sag is located in the northern Huanghua Depression in the Bohai Bay Basin. The Guantao Formation of Neogene in the Sag is the important petroliferous stratum for oil and gas exploration. The sedimentary facies of the Guantao Formation of Neogene are chiefly braided rivers except that the facies are meandering rivers in the middle segment of the Formation. It is the key problem for oil and gas exploration of the Formation to forecast the distribution of advantageous caprocks and to correlate high quality reservoir sand stones accurately.  Based on the principle of high resolution sequence stratigraphy and on the information about lithologic log and welllogs, the author analyzed the patterns of the sequence stratigraphy, the features of sedimentary facies and the combinations of reservoirs and caprocks of the Guantao Formation. The result indicates that the Guantao Formation has developed two kinds of shortterm baselevel cycles which are respectively unsymmetrical cycle formed in low accommodation and symmetrical cycle formed in high accommodation, and four mediumterm baselevel cycles ,which are two unsymmetrical cycles being chiefly half cycles of base level elevating(MSC1, MSC2), one symmetrical cycle(MSC3) and one unsymmetrical cycle being chiefly half cycle of base level descending (MSC4). And both shortterm baselevel cycles and mediumterm baselevel cycles are mainly unsymmetrical ones. During the longterm baselevel cycle of the Guantao Formation,the baselevel elevated slowly and then descended quickly. From MSC1 to MSC4, the sedimentary system of the  Formation has changed first from the combination of alluvial fans and braided rivers to the combination of braided rivers and meandering rivers, then to the combination of meandering rivers and braided rivers. From north to south,while the accommodation of each mediumterm baselevel cycle becomes gradually large, the principal sedimentary facies have gradually changed from gravel channels to sandy channels. Controlled by the framework of mediumterm baselevel cycles,the Guantao Formation in Nanpu Sag  has developed three sets of combinations of reservoirs and caprocks. The upper combination, of which the reservoir and caprocks are the most advantageous, should be the most important target bed of the Guantao Formation in Nanpu Sag for oil and gas exploration.