By using etiolated bean (Phaseolus vulgaris) seedlings, the present work studied the effects of alternative respiratory pathway on chlorophyll content and chlorophyll fluorescence characteristics during greening of etiolated bean seedlings under Pb (lead) or PEG (polyethylene glycol) stresses, to elucidate the physiological role of alternate respiratory pathway of plants under environmental stress. The results showed that: (1) during greening of etiolated bean seedlings, Pb or PEG stress caused significant decreases of the chlorophyll content, F_v/F_m (the potential maximal photochemical efficiency of PSⅡ), F_v′/F_m′ (the maximum quantum efficiency of PSⅡ photochemistry at illumination), Y(Ⅱ) (effective photochemical quantum yield of PSⅡ photosynthetic), and qP (photochemical quenching coefficient), while Pb or PEG stresses increased the levels of NPQ (nonphotochemical quenching), compared to the controls (greening of etiolated bean seedlings without environmental stress). (2) During greening of etiolated bean seedlings, the capacity of the alternative respiratory pathway was increased significantly, compared to the controls. (3) During greening of etiolated bean seedlings under Pb (lead) or PEG stresses, the leaves pretreated with salicylhydroxamic acid (the specific inhibitor of the alternative respiratory pathway, SHAM) exhibited lower levels of chlorophyll content, F_v/F_m, F_v′/F_m′, Y(Ⅱ) and qP, but higher levels of NPQ than the leaves without SHAM treatment. This indicate that inhibition of alternate respiratory pathways will aggravate the inhibition of PSⅡ reaction center activity by Pb or PEG stress and further increase the accumulation of reducing power and increase of heat dissipation. These results suggested that, during greening of etiolated bean seedlings, Pb or PEG stress can significantly reduce the utilization of light energy by PSⅡ and hinder the greening process of etiolated bean seedlings, while the alternate respiratory pathway could alleviate the excessive reduction of PSⅡ under stress conditions, thus alleviating the inhibition of Pb or PEG stress on the greening process to some extent.