In China, waterflooding mature oil fields account for a large proportion of both reserves and production. However, such fields face great challenges in development diagnosis, remaining potential assessment and production optimization. To address these technical difficulties, an intelligent analysis and optimization software system was developed by the author's research group. The system is dual-driven by data and modeling, incorporating expertise in geology, reservoir, engineering, and communication. The software includes six subsystems and more than 500 modules. The core of the self-developed technology is the automatic identification of stratified flow relationships, multi-layer and multi-directional production splitting, real-time water injection optimization, etc. This paper briefly presents some of its core technique, and demonstrates the obvious advantages in terms of fine, real-time, and intelligence using a case of a high water cut oil field in eastern China.