The invention discloses a synthetic method of 3-amino-4-hydroxyfurazan. The structure of 3-amino-4-hydroxyfurazan is represented by a formula shown in the specification. The method which treats 3,4-diaminofurazan as a raw material comprises the following steps: adding 3,4-diaminofurazan and 20-30% (mass) sulfuric acid into a reaction bottle under stirring, adding an aqueous solution of sodium nitrite into the reaction bottle at -5-5DEG C in a dropwise manner under a condition that the addition time is controlled in a range of 1.5-2.5h, reacting at -5-5DEG C for 2-3h after the addition, naturally heating to 20-25DEG C under stirring, carrying out water-bath heating to 40-60DEG C, reacting for 10-20min, cooling to 0-5DEG C, stirring for 20-40min, filtering, washing the obtained filter cake, and drying to obtain 3-amino-4-hydroxyfurazan. The method is mainly used for preparing 3-amino-4-hydroxyfurazan.