This paper for the first time considers a low complexity multiple-input multiple-output (MIMO) mode switching technique between the conventional MIMO and distributed MIMO. By considering the conventional space-time block coding (STBC) and the distributed STBC (DSTBC), we propose a novel mode switching scheme between them to maximize the capacity performance. Since the difference between the STBC and D-STBC mainly comes from the three-directional (3D) distances, the proposed mode switching scheme is based on the jointly consideration of the received signal-to-noise ratio (SNR) at the user equipment (UE) and the 3D distances. Compared with non-adaptive MIMO modes, the proposed adaptive scheme has better capacity performance and thus is more energy-efficient.