The dose deposition of different parts of Aspergillus oryzae spores were analyzed with soft X -ray energies near the K-shell absorption edges of C, N, O elements (4.4nm, 3.2nm and 2.3nm), respectively. At the same time, the spores were irradiated with the three wavelengths of soft X-rays on the soft X -ray microscopy from synchrotron radiation at NSRL, and the survivals were compared. The theoretical analyses showed that the deposition doses of different parts of the spore were varying with X -ray energies because of the effects of C, N, O K-shell absorption edges and elemental contents of the different parts of spore. The experimental studies proved three wavelengths of soft X -rays all had high killing abilities. Among these, 2.3nm wavelength X -rays had higher radiation damage to spore than that of 3.2nm, 4.4nm.