The invention relates to an automatic walking garden trimmer which includes a power locomotive and a trimming device. The power locomotive is rotatably connected with a turntable support whose horizontal rotation is driven by a power device. The turntable support is hinged with a lower support arm and a base cylinder which drives the lower support arm to swing. The end of the lower support arm is hinged with at least two outstretched arms and an extension cylinder used to drive the outstretched arms to swing and adjust outstretching distance. The connecting seat is connected to a sphere. Two sets of trimming devices are arranged on the side of the sphere. The trimming device includes a spiral device and a trimming ring. The spiral device includes a spiral bracket and a sleeve arranged on the spiral bracket. The rotating blade of the trimming device of the present invention can be replaced. The operator can select a suitable blade according to the shape and size of the trimmed shoots, and operate the device to make the device have a wider use range with practicality. In the case of a damaged blade, a new blade can be replaced, saving maintenance time and enhancing work efficiency.
