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In the aforementioned preparation method, the cation in the weak base solution is sodium ion; pKA value of the conjugate acid corresponding to the weak base is 4-11, preferably 5-8. 

In the aforementioned preparation method, the weak base is organic weak base solution, inorganic weak base solution, or combination thereof. The organic weak base is selected from the group consisting of disodium hydrogen citrate, sodium citrate, sodium acetate, sodium propionate, sodium butyrate, sodium isobutyrate, sodium tartrate, sodium oxalate, sodium benzoate, sodium sorbate, sodium malate, monosodium succinate, disodium succinate and combina› tions thereof; preferably, the organic weak base is selected from the group consisting of disodium hydrogen citrate, sodium citrate, sodium acetate and combinations thereof. The inorganic weak base is selected from the group consisting of sodium bicarbonate, sodium carbonate, disodium hydrogen phosphate, sodium borate, sodium sulfite, sodium hydrosul› fide and combinations thereof; preferably, the inorganic weak base is sodium bicarbonate. 

In the aforementioned preparation method, the pH value of the solution obtained from mixing the weak base solution with the water solution containing the compound of formula I is 4.0-7.0, preferably 4.0-6.0, most preferably 4.5-5.5. 

In the aforementioned preparation method, the pH value of the solution obtained from mixing the weak base solution with the mixture solution of water and organic solvent(s) containing the compound of formula I is 4.0-7.0, preferably 4.0-6.0, most preferably 4.5-5.5. 

In the aforesaid preparation method, the concentration of the weak base solution is 0.001-1 mol/L; preferably, 0.01-0.5 mol/L. 

In the aforesaid preparation method, the organic solvent is selected from alcohols or acetonitrile, preferably a Cl-C4 alcohol, most preferably selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, n-butanol, sec-butanol, t-butanol and combinations thereof. 

In another embodiment, a preparation method for the com› pound of formula II is provided in the Invention, comprising the following steps: 

at room temperature, adding the weak base solution to the water solution containing the compound of Formula I or the mixture solution of water and organic solvent(s) containing the compound of Formula I, adjusting the pH value of the obtained solution, thereby obtaining the compound of For- mula II; and said addition is performed slowly with stirring. 

Thus, the Invention provided a preparation method for micafungin sodium so as to obtain micafungin sodium of high purity. 

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## DESCRIPTION OF FIGURES 

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FIG. 6 illustrates the pH value curve of titrating strong acid (hydrochloric acid) with strong base (NaOH solution). 

FIG. 7 illustrates the pH value curve of titrating micafungin solution with 0.1 M solution of sodium bicarbonate. 

