The present invention discloses a children ampicillin sodium compound entity, wherein the preparation method comprises: (1) adding ampicillin to a mixed solution of dichloromethane and triethylamine, cooling, adding a small amount of a sodium 2-ethylhexanoate solution, increasing the solution temperature, adding the remaining sodium 2-ethylhexanoate solution, carrying out suction filtration, washing, and carrying out vacuum drying to obtain an ampicillin sodium crude product; (2) dissolving the ampicillin sodium crude product in purified water, adding active carbon, carrying out stirring decolorizing, and filtering; (3) adding an extractant to the filtrate under the stirring, transferring and filling into a pressure resistance container, removing air bubbles, carrying out sealing oscillation, carrying out temperature control freezing, and taking out; and (4) carrying out liquid-solid separation, discarding the extractant, adding acetone in a dropwise manner at a temperature of 5 DEG C after the solid melts, stirring at a slow speed, growing the grain, filtering, washing, and carrying out vacuum drying to obtain the ampicillin sodium finished product. The children ampicillin sodium compound entity of the present invention has advantages of good solubility, good clarity, low related substance content, good stability, low toxic-side effect, and the like.