Abstract: The spectrum of incident electrons and emitted photons on the anode surface of the diode were calculated and analyzed by Monte Carlo Code MCNP/4C and Matlab, according to relations between the structure, operation parameters of the diodes and emitted electrons and photons spectrum. The parameters for single pulse obtained by several shots were compared, and the distributions of the electron and photon spectrum generated by each shot were calculated. It was investigated that variations of the electrical parameters in the operation of the intense diode influence the stability of the pulsed X-ray spectrum. The result shows that the stability is good with small variations of the electrical parameters of diode.