Using conventional hot-filament chemical vapor deposition system at the substrate temperature of 800 degrees C, diamond crystals and films were deposited on mirror-polished silicon substrate coated with polymer, scratched silicon substrate coated with polymer and scratched silicon substrate, respectively. The [C6H5C](n) polymer, poly(phenylcarbyne), consists of randomly constructed rigid network of tetrahedral hybri dized phenylcarbyne units. The nucleation density of diamond deposited on these substrates coated with polymer is estimated to be about 10(8)-10(11) cm(-2) and higher than that on the substrate only scratched by diamond paste. Moreover, it is found that diamond can grow on the polymer at low substrate temperature (500 degrees C), while diamond crystals are not observed on other polymers, such as Dump oil, polyethylene, etc. The morphology and structure of diamond crystals and films are characterized by scanning electron microscopy (SEM) and Raman spectrum. Some interpretation for the results are given.