Abstract: As the price of the crude oil is low for a long time, it is the tendency to develop offshore oil and gas reservoir more efficiently at a lower cost, and the drilling and completion cost is high in the cost of oil field development. Therefore, it is very important to decrease the cost of drilling and completion. CNOOC have many drilling and completion locations in China, but the efficiency of drilling rigs is different. Through analysis and summary about drilling and completion efficiency, non-productive time, relationship of operation time-effect, based on Wellview of CNOOC daily report of drilling and completion data, continuous drilling and completion improvement system has been developed. In this paper, the overall software architecture of the continuous drilling and completion improvement system is introduced, the function module of the drilling and completion efficiency, non-productive time, operation time-effect relationship are described, the application results of the software are analyzed. The software is helpful for scientific analysis and overall improvement of drilling and completion efficiency.