Using natural light conditions, under different chromium ion mass concentration, the growth of five species of algae were examined. The results showed that: in different wavelengths of light the five species of algae had two districts of its strongest absorption spectra: 420 - 440 nm blue-violet light and 660 nm red parts. Under different chromium ions mass concentrations of 0 - 20.63 mg · L~(-1), the five species of algae growth were subject to different degrees of inhibition, their tolerance to chromium stress varied markedly. After analys...