The invention discloses a protective doorsill for a building resident window. The protective doorsill for the building resident window comprises a window, wherein a protective doorsill is arranged onthe inner side of the window and comprises a left doorsill and a right doorsill; the left doorsill is rectangular; vertical bars are respectively arranged on the left and right sides of the left doorsill; a plurality of transverse bars are connected between the two vertical bars in a longitudinal direction; the transverse bars and the two vertical bars are connected into a whole through a welded manner, and a spacing is reserved between every two of the connected transverse bars; a hinge is connected onto the vertical bar on the left side of the left doorsill; the structure of the right doorsill is the same as that of the left doorsill; the left doorsill is connected onto the inner side wall of a wall on the left of the window by virtue of the hinge; similarly, the right doorsill is connected onto the inner side wall of a wall on the right of the window by virtue of the hinge. After the left doorsill and the right doorsill are closed, two movable ends of the left doorsill 3 and the right doorsill adjacent to each other are locked together by a padlock, so that the inner side of the window is blocked by the left doorsill and the right doorsill. Therefore, the security of children athome is ensured.