A method and a system for dynamic allocation of power for a satellite access network comprises a step for acquisition of a signal representative of an instantaneous power available on board at least one satellite and of a signal representative of the data rate in each resource allocation manager for the satellite access network, a step for conversion, for each resource allocation manager, of the signal representative of the data rate in the resource allocation manager into a value corresponding to the power consumed on board the satellite in order to obtain this data rate, a step for calculating a total power margin equal to the difference between the power available on board the satellite and the sum of the powers consumed by each resource allocation manager, a power allocation step, the value of power allocated being a function of the calculated total power margin.