Using X-ray imaging to deduce equivalent of nuclear explosion is preliminarily discussed.A characterized ring pinhole geometry model is established.MCNP4C is used.The source area,determinaton of E_c,influence of ring width,equivalent temperature and incident angle of X-rays are simulated.It is poined out that the source area should be selected as S₀=6.25πcm² and E_c=2×10^-8 MeV.Energy response and angle response should be considered.Characterized ring pinhole models at equivalent temperatures 1.4 keV and 3.8 keV and at incident angles 0,1,2,3,4,5,6 degree are simulated.