The measurements of atmospheric sulphur dioxide (SO2) and ozone (O3) using optical fiber based on light-emitting diode (LED) long-path differential optical absorption spectroscopy (LP-DOAS) system are presented. Two ultraviolet (UV) LED with different emission wavelength ranges are used as the light sources. The measurement results are compared to the SO2 and O3 levels measured by the conventional LP-DOAS with xenon arc lamp light source. The comparison result shows that they are in good agreement, and the correlation coefficients of SO2 and O3 measurements are 0.987 and 0.992, respectively. With 700 m measurement path, the detection limit of SO2 and O3 are 0.8×10-9 and 7.4×10-9, respectively. This indicates that the optical fiber-based LP-DOAS improves the light coupling efficiency, and is feasible for the detection of ultraviolet absorbing trace gases using UV-LED as the light source.