The present invention discloses an active power distribution network situation awareness system and method based on distributed monitoring and multi-source information fusion. The system includes a multi-source information fusion unit, a source load prediction unit, a distribution network power flow analysis unit, a power distribution network state estimation unit, a power distribution network risk analysis and early warning unit and a situation display visualization unit. The method comprises the following steps that: 1) fusion analysis is performed on a plurality of kinds of information of a distributed monitoring system and a data interaction bus; 2) on the basis of fusion information and user behavior prediction, distributed power source prediction and feeder-level load prediction are carried out; 3) power distribution network state estimation is carried out according to real-time measurement data and load prediction data; 4) on the basis of a source load prediction result and a power distribution network state estimation result, distributed power source-containing power distribution network power flow analysis is carried out; 5) risk quantitative analysis and early warning for various kinds of operation scenes are carried out through using a multi-attribute risk assessment method on the basis of the operation power flow and operating state of a power distribution network; and 6) the operating state and situation change of the power distribution network are displayed in an overall and detailed parallel display manner.