Volatile organic compounds (VOCs) is one of the key precursors of atmospheric ozone (O3), whose concentration variation influences directly the level of the photochemical pollutant O3. During Beijing Olympics, VOCs were measured near the Beijing National Stadium. Two and half-hour integrated canister samples were collected and analyzed in the morning and afternoon of each sampling day. Simultaneously, concentration, potential ozone production and sources of VOCs in the atmosphere of Beijing were studied. And the results indicated that the total VOCs species had higher concentrations in the morning (34.38 x 10(-9)), and lower in the afternoon (27.13 x 10(-9)), where the concentration of alkanes was the highest, and aromatics and alkenes came next. However, the concentrations of alkenes in the afternoon were significantly lower than those in the morning, which was 28%, and aromatics (26%) and alkanes (15%) came next. 1,2,4-Trimethylbenzene has the highest propylene-equivalent concentration (8.05 x 10(-9)C), and m/p-xylene (6.97 x 10(-9)C), toluene (6.41 x 10(-9)C) and 1,3,5-trimethylbenzene (5.64 x 10(-9) C) came next. Aromatics (47%) gives the most significant contribution to the production of O3 in the atmospheric VOCs of Beijing, and then were alkenes (40%) and alkanes (13%). Automobile emissions accounted for approximately 28% of the total VOCs, and solvent volatilization (19%), LPG leakage (15%) and industrial sources (12%) came next, from which Beijing may decrease the atmospheric VOCs.