Using the three dimensional and paralleled JMCT Monte Carlo code, the backscattered photoelectric yields and electron energy spectra are calculated for the cases that black body X-ray sources of temperatures of 1, 3, 5, 8 keV impact on the material surfaces of Al, SiO2 and Au respectively. The simulation results are consistent with the results in references, which verify the validity of the code. Then the typical photon-electron transport example in SGEMP for black body X-rays impacting on a cylinder cavity is calculated. Half of the side-face of the cylinder emits photoelectrons in the case that the black body X-rays of temperature 1 keV and fluence 1 J/m2 impact on the side-face of the cylinder. The photoelectron parameters of photoelectric yield, energy distribution and angular distribution related with azimuth are calculated. The results show that obliquely incident X-ray could induce higher photoelectric yields than normally incident X-ray and the distributions of photoelectrons are all very close to cosine distribution.