The invention discloses a preparation method of X-ray radiation preventing cellulose fiber, which comprises the steps of preparation of a modified nanometer barium sulfate ethylene glycol solution, preparation of a viscose stock solution, preparation of a spinning stock solution and spinning formation. The preparation method of the X-ray radiation preventing cellulose fiber has the advantages that the direction application for the production of cellulose fiber is obtained through adding an X-ray shielding agent; the problems of scattering and secondary agglomeration are avoided; the scattering in the fiber is uniform; the mechanical performance is excellent; the spinning processing performance is outstanding; the X-ray shielding rate is high and not lower than 62%; the durability is high; and the X-ray shielding rate is still higher than 45% after being cleansed for 50 times. The preparation method for X-ray radiation preventing cellulose fiber can be widely used for making the clothes of the workers contacting the X-ray for a long time and the non-woven cloth making industry, has a reasonable and simple technology, and is suitable for industrialized production.