The paper analyzes the concept of information safety and discusses the relationship among member parts of information security system frame. Taking the security situation of County-city Power Grid’s data net system as an example，the weaknesses of the net structure and security strategy dispose are analyzed. According to the system structure，the future task and safety requirements on the net basic platform，operation system connector and security protection are concluded；relative solutions are proposed. Based on the principles of net safety design and the characteristics of different safety technologies，a new project is put forward. Through this new system，the problem of lacking security protection measurements，which has been existed in power industries for a long period，has been solved. It can provide the ability of timely fault finding，corresponding solving methods，the capabilities of precaution and instant upgrade，which is an efficient and optimized power grid data network system.