A preparing method of edible magnesium chloride is disclosed. The method includes steps of A) preparing a first mother liquor, B) subjecting the first mother liquor to first evaporation at 100-110 DGE C, and performing hot filtration to obtain a filtrate that is adopted as a second mother liquor, with the water loss rate of the first mother liquor in the first evaporation being 4.1-16.3%, and C) subjecting the second mother liquor to second evaporation, cooling until the temperature is lower than 90 DEG C, and performing solid liquid separation to obtain a solid phase that is the edible magnesium chloride, wherein the first mother liquor comprises Na<+>, K<+>, Mg<2+>, Cl<->, SO4<2-> and H2O, and the first mother liquor comprises 0.1-0.2% by mass of the Na<+>, 0.05-0.1% by mass of the K<+>, 8.4-9.5% by mass of the Mg<2+>, 24.5-28% by mass of the Cl<-> and 0.05-0.1% by mass of the SO4<2->, with the balance being the H2O. The method is simple and avoids a problem that mother liquor entrainment exceeds standards due to one-time evaporation.