In our experiment described in this paper, the single pulse of the picosecond laser (λ=0.527 μ) from bhe output of a frequency-doubled mode-locked phosphate Nd glass laser at λ=1.054同μm was used as the exciting light source. The lifetimes of the excited singlet states S1 of the organic biological macromolecules haema-toporphyrin and lactoflavin were measured with streak camera. The quenching effect of oxygen molecules on the lifetimes was discussed preliminarily.