This paper deals with the eftect of application of organic materials on the optical properties of humic acids (HAs) from brown earth, meadow soil and paddy soil. The results obtained are summarized as follows: Application of organic materials led to the decrease of E₂₆₅,E₄₆₅ and RF values and increase of Δlog K of HAs. The shoulder-like absorption at 285nm originated from ligrin in ultraviolet spectra of HAs from the organic manure amended soil became more apparent as compared with that of the soil without organic manure application. The maximum-intensity wavelengths of fluorence excitation spectra(λ_ex) and the intensity of fluorescence emossion excitation spectra of HAs were reduced by application of organic materials. However, the maximum-intensity wavelengths of fluoresce emission spectra(λ_em) remained unchanged (about 546nm),no matter whether organic material was applied or not.