Cotton fibers were firstly treated by nano TiO₂ coating via a dip-coating method, and then Pd nanoparticles (NPs) were deposited onto the surface of TiO₂/cotton fiber (TC) to acquire the Pd/TiO₂/cotton fiber composite (PTC) catalyst by a combined impregnation and NaBH₄-reduction method. The obtained PTC sample was used for room-temperature catalytic oxidation of formaldehyde (HCHO) and the influence of Pd content on catalytic activity was investigated. The results reveal that the air resistance of PTC catalyst is much lower than that of the powder-like sample, which is of vital importance for its actual application, and HCHO can be catalytically decomposed into CO₂ and H₂O over PTC. The catalytic activity of PTC increases with increasing of Pd content in the range of 0.25-1.0 wt%. Owing to the merits of low air resistance, light mass, flexible properties, good efficiency of the PTC catalyst, it can be a good candidate in actual indoor air purification and related catalytic processes.