Based on the characteristics of soft X-ray spectro-microscopy at Shanghai Synchrotron Radiation Facility (SSRF)
we explore in this paper the possibility of performing soft X-ray CDI(coherent X-ray diffraction imaging) for 3D elemental mapping.The dual-energy contrast analysis algorithm of CDI is deduced.The experiment method is simulated with Fe as the element under analysis in an organic sample(with C as the major element beyond analysis). The analysis sensitivity is estimated
and noise effect on the elemental mapping is analyzed.The results are of help in developing the soft X-ray CDI application.