Under the trend of low-carbon economy development worldwide and the requirement on energy saving and emission reduction during the twelfth five-year period in China， the demand for security and reliability in power system operations is very high. The environmental-friendly and economical development of electricity power system is also becoming an compelling issue. How to form a reliable and feasible low-carbon power system to cope with the changing external environment is a now serious business. From the perspective of secure and reliable power supply， the basic functions of low-carbon power system required are analyzed， and four mechanisms to realize low-carbon power system and two carbon reduction conversion methods are presented. The objective function of a smart grid is also discussed in terms of clean power generation， scheduling optimization， efficiency improvement， power consumption as well as investment optimization aspects. Finally， the specific technical paths for a smart grid to achieve low-carbon power system are proposed based on clean production， losses reduction， power consumption savings， and investment optimization.