The LLFT X ray holography is studied by optical experimental simulation on the whole process from recording to digital reconstruction. A He Ne laser is used as light source and the recording setup is similar to that in LLFT X ray holography. Experimental results are given and a comparison between digital reconstruction and optical reconstruction is made. Some problems in this kind of recording style are analyzed. As a result, we point out that in X-ray hologram recording the +1st diffraction of zone plate can be taken as reference point source directly, rather than filtered by a small hole. The feasibility for eliminating the nonlinearity of recording medium is analyzed. The disturbance of the interference from the different diffractions of zone plate is emphasized.