A tree supporting and fixing device for landscaping comprises a first clamp plate, a second clamp plate, a supporting and fixing frame, and a ground plugging fixing device; the supporting and fixing frame is arranged on the first clamp plate, and an arc fixing slot is arranged on the second clamp plate; the supporting and fixing frame comprises a fixing rod, a moving rod, an arc bending plate, a fixing ring, and an annular sealing rubber rib; the lower end of the fixing rod is arranged in the middle part of a first semispherical rotating bearing, and two fixing supporting rods are symmetrically arranged on the fixing rod; a convex face of the arc bending plate is arranged at the top end of the moving rod through a second semispherical rotating bearing, an annular buckle is arranged on thesecond clamp plate; the annular buckle is connected with the arc bending plate through the annular sealing rubber rib; the ground plugging fixing device comprises ground plugging point rods and a fixing steel wire, the middle part of the ground plugging point rod is provided with a through hole; the fixing steel wire crosses through the through holes on adjacent ground plugging point rods. The device can rapidly and stably fix and protect the trees required to support, and can be repeatedly used and applicable to trees with different diameters.