In this work, titanium nitride (TiN) coating was used as a passive layer to inhibit metal catalytic coking during hydrocarbon fuel cracking on the microchannel inner surface of stainless steel 304 (SS304) tubes. In order to obtain an inert and effective passive coating, TiN coating was prepared in SS304 tubes with 2 mm inside diameter and 700 mm length by atmospheric pressure chemical vapor deposition (APCVD) using a TiCl4–H2–N2 system. The coating’s thickness, phase composition, morphology, and chemical composition were investigated by metalloscopy, X-ray diffraction, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), respectively. Characterization results indicated that TiN coating had a relatively complete cubic-phase crystal form with a N/Ti ratio of 1:1, presenting small star-shaped crystals on the whole. The inhibition effects of TiN coating on the morphologies and amounts of coke were studied by SEM and EDX after n-hexane thermal cracking at 600 °C and 3.3 MPa for 2...