The invention discloses a municipal tree protective device which comprises a coating mechanism and a support mechanism. The coating mechanism is coated on a tree trunk, support effects can be realizedby the support mechanism, the coating mechanism comprises a plurality of coating plates and tension springs, and the adjacent coating plates are connected with one another by the tension springs. Themunicipal tree protective device has the advantages that influence on tree thickening can be prevented; a tree trunk portion can be coated by the coating plates and can be supported by the support mechanism, tree trunk diameter change requirements can be met by the expansion and contraction quantities of the tension springs when the diameter of the growing tree trunk of a tree is increased, accordingly, the coating mechanism can be tightly coated on the tree trunk, and mechanical damage to the thickened tree can be prevented.