The experiments were performed at HI-13 tandem accelerator at the Chinese Institute of Atomic Energy （CIAE）, in which the L-shell X-ray relative production cross section was measured for solid targets Au bombarded by 20—50 MeV O5+ions. The ratios of Au L-subshell production cross sections σ（Lβ）/σ（Lα），σ（Lγ）/σ（Lα），σ（Ll）/σ（Lα） have been calculated according to the experimental data. The results are compared with the predictions of the ECPSSR theory. Reasonable agreement between theory and experiment was obtained.