The invention discloses an adjustable trimmer for a four-leaf rose groove on a shrub top surface and belongs to the technical field of landscaping greening and trimming. A track generation motor drives a crankshaft to rotate; the crankshaft drives a tie-rod to rotate and then drives a planetary wheel to rotate and revolve; a motion track of a central supporting shaft connected with a planetary rod on the planetary wheel via an adjustable planetary rod sleeve assembly is a regular four-leaf line track; with adjustments of the adjustable planetary rod sleeve assembly, patterns with tangent four-leaf track lines or patterns with separated four-leaf track lines can be selectively generated; during the motion of the central supporting shaft, an arc guide assembly and a guide bearer assembly can drive upward and downward movements of a central sleeve to form a spherical cambered regular four-leaf motion track. Shrub surface area receiving sunlight is increased, shrub curve reflecting noise can be increased and reflection direction can be changed; and further, vehicle noise can be lowered, so drivers on a high position can dynamically feel and space heterogeneous can be provided for pedestrians.