The generation of hot electrons and the coupling efficiency from laser to hot electrons are very important issues in fast ignition of inertial confinement fusion, which are important for optimizing the parameters of laser pulse and plasma and reducing the requirement for laser pulse. Laser interaction with nanolayered target is considered to be one of available ways of enhancing the coupling efficiency of laser to hot electrons. In order to understand the heating mechanism of hot electrons in the interaction between laser and nanolayered target in great detail, two-dimensional particle-in-cell simulation is carried out in this paper. Reflux for cold electrons moving to the interaction-face and then being accelerated near the interaction-face is detected by observing the tracks of electrons in the nanolayered target. It is found that the energies of inverse electrons are far smaller than those of forward electrons and the most inverse electrons are from the reflux of cold electrons by investigating the variations of the electron density and the electron energy density in one laser period. The J B heating mechanism is found to be a dominate mechanism in the generation of hot electrons by comparing the field and the locations of hot electrons at different times.