Method for producing sodium borohydride

The invention relates to a preparation method of sodium borohydride. Wherein when a sodium borate compound, an aluminum powder, and a fluoride powder are mixed and reacted at a temperature of 560 DEG C or less in a sealed container filled with hydrogen gas, the mixture is stirred using a stirrer in the sealed container, and the reaction is performed at a temperature of 560 DEG C or less. The stirring height ratio (X) represented by the following mathematical formula (I), which is determined by the minimum gap (a) between the stirrer and the bottommost part of the sealed container in the gravity direction, and the raw material input height (b) at which the raw material is input into the sealed container, is 75% or more, X = [(b-a)/b] * 100 formula (I). 本发明涉及一种硼氢化钠的制造方法。其中，当在充满氢气的密闭容器内，将硼酸钠类化合物、铝粉末和氟化物的粉末混合，在560℃以下的温度反应时，在上述密闭容器内使用搅拌子进行搅拌，通过上述搅拌子与上述密闭容器的重力方向的最底部之间的最小间隙(a)与将原料投入上述密闭容器内的原料投入高度(b)所确定的下述数学式(I)所表示的搅拌高度比(X)在75％以上，X＝[(b－a)/b]×100式(I)。