The invention discloses a WSN node energy monitoring method and system based on data source tracing, and the method comprises a data source tracing stage and a node energy consumption monitoring stage. The data source tracing stage comprises the steps: carrying out the tracing of a data package received by a base station, and obtaining a set of sensor nodes participating in the forwarding of current data. The node energy consumption monitoring stage comprises the steps: subtracting a single-hop forwarding energy consumption value from the current energy value of each sensor node in the set according to a data forwarding node set obtained at the data source tracing stage, storing the remaining energy value into the energy consumption record table of the node, and monitoring the remaining energy of the sensor nodes through the energy record table.