The surface modification of polyethylene (PE) and polypropylene (PP) was investigated by UV light/ozone (UVO) treatment. The surface oxygenation was determined by electron spectroscopy for chemical analysis (ESCA). As shown from ESCA spectra, after UVO treatment, oxygen-containing functional groups, such as carbonyl, carboxyl, and ether groups, were produced in the sample surface. The dependence of oxygenation extent (as measured by O-1s/C-1s value of ESCA spectra) on different experimental conditions, such as irradiation time, temperature, and O-2 flow rate, was obtained. It was shown that after UVO treatment at suitable conditions the surface properties of polyolefine samples, such as hydrophilicity, adhesion property, and dyeability, were improved remarkably. Furthermore, UVO treatment in short time does not have notable effect on the ageing property. It was concluded that UVO treatment is a promising technique to modify polyolefine surface properties.