Abstract: Improper development of reservoirs with gas cap as well as edge water can usually lead to gas and water breakthrough, which could cause irreversible reserve costs. According to the characters in Block B, such as certain amount of gas cap, medium oil ring width and weak edge water, flow mechanism of reservoir was studied. Based on them, a strategy of mixing with water barrier flooding in gas cap, edge water flooding and inner scattered flooding was proposed, and then the main factors influencing developing effect were pointed out. Meanwhile, other reservoir and engineering methods were adopted to comply with the flooding, which include reasonable producing differential pressure, flowing pressure boundary, injection-production ratio, water and gas avoid perforation. With the development policy and measures implementation, considerably well developing results were achieved. Water cut and GOR remain stable, and all the development indexes show fine exploiting feature. It provides reliable theory and practice guide for this kind of reservoirs.