The invention relates to a method and a device for distributing energy of a composite power source of a fuel cell vehicle, The device comprises a first DC conversion circuit, a second DC conversion circuit, a first determination module, a second determination module, a control module and an energy distribution module. The control module determines a reference demand current signal according to a change rate of a first disturbance parameter. The energy distribution module transmits the reference demand current signal to the first determining module and the second determining module according tothe energy distribution coefficient. The first determining module determines the first duty cycle signal according to the reference demand current signal and the second disturbance parameter change rate. A second determination module determines a second duty cycle signal according to the reference demand current signal and the third disturbance parameter change rate, At present, that distributionmethod is sensitive to system parameter disturbance and load variation, has poor disturbance rejection performance and poor robustness, is insensitive to system parameter disturbance and load variation, and has better disturbance rejection and robustness. The invention can solve the problem that the current distribution method is sensitive to system parameter disturbance and load variation, and has poor disturbance rejection performance and poor robustness.