The invention relates to a dynamic loss reduction method for a distribution network and a synthesized loss reduction system of a distribution network. A principle that an electric field and a magnetic field are mutually symbiotic and affected is applied for dynamically realizing electromagnetic balance; the treatment of'peak load shifting'is carried out on the current difference value between three-phase unbalanced currents caused by the dynamic unbalance of the power used by a three-phase load at the secondary side of a distribution transformer so as to lead the current difference value to approach balance, reduce a zero sequence current and the unbalance degree of the three phases, and restrain a harmonic, thereby realizing the self loss (loss on transmission) of the distribution transformer and the line loss (the copper loss of the line) at the first side and the secondary side of the distribution transformer; the synthesized loss reduction system of the distribution network realizes the synthesized loss reduction management of the distribution network, the loss on transmission of the distribution transformer as well as the automatic measuring and accounting on the data of the copper loss of the line at the first side and the secondary side thereof; the system also realizes the remote automatic collection on the power data of the distribution transformer in the same time as well as the accounting of the line loss of a distribution line, calculates and accounts the line loss of the distribution network, calculates and analyzes the loss reduction as well as analyzes the benefits of energy saving and emission reduction.