Low-temperature plasma treatment is a kind of environmentally friendly surface modification technology, which has been widely used to modify various materials in many industries. In this study, cold gas plasma was used to treat polypropylene (PP) fibres. The effects of plasma treatment on the surface morphology and wettability of the fibres were characterized using atomic force microscopy (AFM) and dynamic contact angle measurement. The AFM observations revealed the changes in the surface morphology of the fibres caused by plasma treatment. The dynamic contact angles (DCA) were measured based on the Wilhelmy principle. The DCA technique was able to examine the advancing contact angles and receding angles of the fibres. The study revealed that the plasma treatment could considerably reduce both advancing contact angle and receding angle of polypropylene fibre. The surface roughness was the main reason for reducing the receding contact angle, while the advancing contact angle was more related to the surface properties of the fibres.