The invention relates to a 10kV power distribution network dynamic load flow online calculating method. According to the calculating method how the motions of a reactive compensation and voltage regulation device change the power distribution network load flow can be quantitatively analyzed, and a built 10kV power distribution network and devices which can change the state of the power distribution network and include a power transformer substation on-load voltage regulation switch, a 10kV circuit capacitor, a 0.38/0.22kV capacitor, an APF and a series voltage regulation transformer are utilized. A dynamic equation is derived according to universality of a power distribution load flow static equation. Through the calculating method, the influences of the motions of the reactive compensation and voltage regulation device on the power distribution network can be accurately predicted, economic operation optimization of the power distribution network becomes possible, and the difficult problem of existing 10kV and below power distribution network dynamic load flow online calculation is solved. The 10kV power distribution network dynamic load flow online calculating method is accurate, stable, targeted and wide in application range.