A modular vegetative retention tank includes a trough-shaped body, which is divided into three accommodating spaces by a first partition and a second partition, which are respectively filled with different filling materials. Both the first partition and the second partition are perpendicular to each other, and both are perpendicular to the groove bottom of the groove-shaped body. The first partition divides the trough-shaped body into a first receiving space and a remaining space. The second partition has overflow holes and divides the remaining space into a second accommodating space and a third accommodating space. The bottom of the second accommodation space is in communication with the bottom of the first accommodation space. The third accommodation space is not connected to the bottom of the other two accommodation spaces. During maintenance management, if the filling material in any one accommodation space needs to be replaced, it will not affect the status in the other two accommodation spaces, so it can save maintenance time and cost.
