A graphics processing unit (GPU) and a management method of the GPU are provided. The GPU includes at least one graphics engine and an engine manager. The graphics engine performs a video decoding function or a graphics rendering function according to a graphics command from a driver software. The engine manager records a workload index of each graphics engine. The engine manager also adjusts the work ability of one of or more of the at least one graphics engine according to an adjustment command from the driver software. The driver software provides the adjustment command according to the workload index.