For studing the transport of hot electrons in solid targets by transition radiation, the image pattern of spatial distribution and spectrum of optical emission were measured at the normal direction from the rear side of targets employing optical CCD camera and OMA optical multi-channel spectrometer on the 100 TW femtosecond laser facility.The image pattern of spatial distribution has a disc-shape, in which is distributed a bright localized signal, which shows the filament effect during hot electron transport. The spectrum of optical emission has sharp peaks near the 3 and 3/2 multiple of the fundamental frequency, corresponding to the third-order harmonic and 3/2-order harmonics, respectively, which is ascribed to the coherent transition radiation (CTR) generated by microbunches of hot electron beams produced in transport. The intensity of transition radiation decreases with the increase of target thickness.