Pure cubic beta-Fe2O3 crystal, which can absorb visible light (< 650 nm) on account of the bandgap of 1.9 eV as a direct bandgap semiconductor, was employed as a low-cost and non-toxic catalyst for photo-Fenton reaction in this article. Diverse organic contaminants including rhodamine B (RhB), methyl orange (MO), alizarin red (AR) and phenol can be effectively degraded. In particular, the degradation of RhB were investigated detailedly. As such, hydroxyl radicals (.OH) were verified to act as considerable active species for the process by using terephthalic acid as an indicator. Degradation mechanism and intermediates of phenol in the photo-Fenton reaction was discovered by virtue of liquid chromatography-mass spectrometry (LC MS). Notably, hydroxylation of phenol generated some intermediates, which are converted into H2O and CO2 eventually.