Abstract Magnetic reconnection has been proposed to play an important role in energy dissipation in space plasma. The diffusion region is an essential place for generation of energetic electrons. However, the mechanism responsible for the generation of these energetic electrons in such a confined region remains elusive. Here a diffusion region of asymmetric reconnection is observed at the turbulent magnetopause. The diffusion region is a rather structured region where two dynamical filamentary currents at subion scale were observed. Intense electron flow and nonideal electric field inside the filamentary currents induced significant energy dissipation. Concurrently, the electron parallel temperature between the current layers increases from 58 to 80 eV. Direct evidence indicates that the electrons inside the three-dimensional diffusion region are accelerated by the parallel electric fields inside the current layers and are effectively heated by the turbulence between them.