AMS (advanced metering system) communicates with vast smart meters via GPRS to collect metering data and send control message, is exposed to the security risk of cyber attack and sensitive data leakage. The application of cyber security situational awareness technology in AMS is helpful to deeply and comprehensively analyze and evaluate the security status of the system. Based on the analysis of the security threats of AMS, a multi-source situational awareness, analysis and evaluation scheme is proposed, which integrates network security, system security, data security and other factors. This paper analyses and designs a unified model of multi-source detection log information collection and formatting, eliminating the problems of relatively isolated detection data and insufficient evidence after the existing system is attacked. Based on the multi-source data fusion and the application of fuzzy reasoning technology, the correlation and risk of network attacks are deduced, which enables the system to detect complex network attacks and evaluate the correlation attacks.