A new method unfolding soft X-ray spectra for a soft X-ray spectrometer (SXS),which is based on maximum entropy principle (ME),is put forward.The spline fit method is used to smooth the discontinuities between the channels at the filters edge responses.The convergent speed of ME is rapid,the stability and the deconvolution accuracy appear to be good.ME's unfolding error can achieve 5%.The method is capable of unfolding the soft X-ray spetra for the soft X-ray spectrometer.