Abstract: The single crystals oftwo organic semiconductor, pentacene（PEN）and methoxyloligo- phenylenevinylene（MOPV）, have been prepared on SiO₂/Si substrate by vacuum vapor deposition. The deposition was carried out in a vacuum system with multiple heating zones and controlled gas inlet. The shape of PEN and MOPV crystals are strongly dependent on the deposition condition and flake and line shape crystals were successfully obtained under optimized conditions. The growth of MOPV crystals followed Volmer- Weber model. Strong fluorescence anisotropy was observed on the MOPV nanofibers by polarizer fluorescence microscope.