The present disclosure relates to a ray generating device and a control method thereof. The ray generating device includes: an electronic beam generating device (2), configured to generate a plurality of electronic beams; a microwave generating device (4), configured to generate a microwave; a microwave circulator (5), having a power input port and at least two power output ports, the power input port being connected to the microwave generating device (4);a plurality of accelerating tubes (3), connected to the electronic beam generating device (2) and respectively connected to the at least two power output ports, configured to respectively receive a plurality of electronic beams, and accelerate the plurality of electronic beams respectively through microwaves received from the at least two power output ports, so as to respectively generate a plurality of rays having at least two different energies; and a controller (1), configured to perform chronological control on microwave power of the microwave generating device (4), and chronological control on beam loadings of the electronic beams generated by the electronic beam generating device (2) and respectively corresponding to the plurality of accelerating tubes (3).