The invention discloses a preparation method of high purity titanium, relating to the field of metallurgy and chemical industry. The preparation method comprises the following steps: heating the purified TiCl4 solution, controlling the flow rate of the TiCl4 by argon gas, heating metal magnesium and controlling the flow rate of the metal magnesium by the argon gas; sending the measured TiCl4 gas and the magnesium steam into a reactor which is heated to 600 to 1200 DEG C, and causing the measured TiCl4 gas and the magnesium steam to react with each other so as to obtain metal titanium and magnesium chloride; taking the metal titanium and the magnesium chloride out respectively from the bottom and middle of the reactor; carrying out fused salt electrolysis on the magnesium chloride to obtain metal magnesium and chlorine; returning the metal magnesium to the reduction process, and using the chlorine for producing the TiCl4, thereby realizing the closed cycle of the preparation process; and washing the metal titanium by 1% hydrochloric acid and deionized water repeatedly, drying and packaging to obtain the high purity titanium. The invention has the advantages that the metal magnesiumtakes part in the reaction with the form of gaseous phase, the impurities in the magnesium raw material can not enter the product, therefore the product has higher purity; and the preparation method of the invention can be used for continuous production, therefore the production cost is lower.