The invention discloses an energy distribution method of a range-extended electric city bus. The energy distribution method includes: detecting a running condition parameter, judging whether the running condition parameter is smaller than a first preset value and larger than a second preset value or not, if so, sending out control commands to close an auxiliary power system and lead a power battery to provide energy; if not, acquiring a current SOC value of the power battery, further judging the current SOC value is larger than a stop-setting value of the auxiliary power system, if so, sending out the control commands to close the auxiliary power system and lead the power battery to provide the energy; if not, sending out the control commands to start up the auxiliary power system to provide the energy for the city bus and to have the power battery recharged. According to the energy distribution method, energy is distributed on the basis of the three parameters of the first preset value, the second preset value and the stop-setting values of the auxiliary power system, so that overall optimization of energy distribution is realized; especially in the third stage, the power battery is fully utilized to provide the energy, and economical efficiency of the city bus is improved.