The invention provides a power line communication simulation method and system based on energy detection. The method comprises steps as follows: determining a reference parameter Et according to carrier energy average intensity E0 and noise average intensity N0 of a power line; enabling an uplink pathway and a downlink pathway of the power line; presetting sampling frequency; sampling voltage intensity of the uplink pathway and the downlink pathway according to the sampling frequency, and acquiring an energy mean value Ea of the uplink pathway and the energy mean value Eb of the downlink pathway through calculation; comparing the energy mean value Ea and the energy mean value Eb with the reference parameter Et respectively; when the energy mean value Ea is larger than the reference parameter Et, setting a voltage value output by the downlink pathway as zero; when the energy mean value Eb is larger than the reference parameter Et, setting a voltage value output by the uplink pathway as zero. Signal echo interference is avoided during power line communication, and the data transmission accuracy is guaranteed.