Disclosed is a device for adding water into milk powder, comprising a milk bottle (1) and a milk powder box (2), wherein the milk powder box (2) comprises a box body component (20) and a box bottom (30), the box body component (20) comprises a box body (21) and a box body connection part (22), the box body (21) comprises a box body base (211) and a first sealing part (212) formed integrally with the box body base (211), an upper part of the box body base (211) is cooperatively connected to a nipple, a lower part of the box body base (211) is cooperatively connected to an upper part of the box body connection part (22), and a lower part of the box body connection part (22) is cooperatively connected to the milk bottle (1) the box bottom (30) is sheathed on a bottle mouth of the milk bottle (1), with an annular belt of an outer ring of the box bottom (30) being provided with a leak hole (327), and the box bottom (30) comprises a box bottom base (31) and a second sealing part (32) integrally formed with the box bottom base (31) and the box body (21) is movably connected to the box body connection part (22) and can move relatively longitudinally to form a first operation position which has a milk powder placing cavity isolated, in a sealed manner, from an inner cavity of the milk bottle (1), and a second operation position which has a milk powder channel isolated from the outside in a sealed manner for adding water into the milk powder. The device for adding water into milk powder has a simplified structure and improved reliability and the durability of the sealing members.Linvention concerne un dispositif pour ajouter de leau dans du lait en poudre, comprenant une bouteille de lait (1) et une boîte de lait en poudre (2), la boîte de lait en poudre (2) comprenant un composant corps de boîte (20) et une partie inférieure de boîte (30), le composant corps de boîte (20) comprend un corps de boîte (21) et une partie de raccordement de corps de boîte (22), le corps de boîte
