A modular tree foundation construction assisting device. The device is obliquely arranged on one side of a tree (200) to support the tree (200). The device comprises a positioning device (1), a supporting device (2) and a connecting component (3) communicated with each other. The positioning device (1) is buried under the ground of one side of the tree. As a foundation for stabilizing, the positioning device (1) comprises a first underground vertical pipe (11), a second underground vertical pipe (12), an underground transverse unit (13) and an underground connecting piece (14). The supporting device (2) is positioned on the ground of one side of the tree and used for stabilizing a trunk of the tree. The supporting device (2) comprises a first aboveground vertical pipe (21), a second aboveground vertical pipe (22), an aboveground transverse unit (23) and an aboveground connecting piece (24). The connecting component (3) comprises a first connecting sleeve (31) respectively connected and communicated with the first underground vertical pipe (11) and the first aboveground vertical pipe (21), and a second connecting sleeve (32) respectively connected and communicated with the second underground vertical pipe (22) and the second aboveground vertical pipe (32). The device can effectively support the tree to facilitate the growth of the tree. Furthermore, the device is convenient to tend the tree and easy for subsequent treatment.Linvention concerne un dispositif daide à la construction de fondation darbre modulaire. Le dispositif est agencé obliquement sur un côté dun arbre (200) pour soutenir larbre (200). Le dispositif comprend un dispositif de positionnement (1), un dispositif de support (2) et un élément de raccordement (3) en communication lun avec lautre. Le dispositif de positionnement (1) est enfoui sous le sol dun côté de larbre. En tant que fondation de stabilisation, le dispositif de positionnement (1) comprend un premier tuyau vertical souterrain (11), un seco
