This study presents a novel process combining hot filament chemical vapor deposition (HFCVD) method and polishing technique to fabricate micro/nano-crystalline multilayered ultra-smooth diamond (USCD) films on the interior-hole surface of conventional WC-Co drawing dies.Scanning electron microscopy (SEM), surface profilemeter, Raman spectroscopy and X-ray diffraction (XRD) are employed to provide a characterization of as-deposited USCD films.The results exhibit that as-deposited USCD films present a ultra-smooth surface, its surface roughness values (Ra) in the entry zone, drawing zone and bearing zone are measured as 25.7 nm, 23.3 nm and 25.5 nm respectively.Furthermore, their friction properties are examined in both dry sliding and water-lubricated condition, comparing with conventional MCD films and uncoated WC-Co samples.Ball-bearing steel, copper and silicon nitride balls (φ4 mm) are used as the counterpart materials.The results show that the USCD film presents much superior friction properties.For a given counterpart material, its friction coefficient, in either dry sliding or water-lubricating condition, is always the lowest, and also presents similar wear resistance with conventional MCD films.Finally, the working lifetime and performance of as-fabricated USCD coated drawing dies are examined in producing low-carbon steel pipes in dry and water lubricating conditions.In water lubricating drawing condition, its production significantly increases by a factor of above 20 comparing to the conventional WC-Co drawing dies.