Abstract: The difference of leaf anthocyanin content between tomato seedlings grown under sulfur lamp and xenon lamp, and the difference between WT and photomorphogenetic mutant phyB1phyB2 were taken advantage to study if anthocyanin could act as a protectant for photosynthetic apparatus exposed to low temperature and low light. Chlorophyll fluorescence was chosen as the approach to assess the extent of photosynthesis apparatus photodamage. The results indicated that, exposure to low temperature and low light (5oC, 100 μmol photons m-2 s-1) markedly inhibited PSⅡ activity, but slightly affected PSI activity. After treatment for 3h, PSⅡ Fv/Fm in tomato leaves grown under sulfur lamps and under xenon lamp decreased to 76.3% and 63.3% of pretreatment, respectively; Similarly, Fv/Fm decreased to 64.3% of pretreatment for WT seedlings and 53.7% for phyB1phyB2 seedlings. After tomato plants grown under sulfur lamp or that of widetype was not able to accumulate anthocyanin, no significant difference was observed in Fv/Fm between plants grown under different light environment or between the two genetypes after treatment with low temperature and low light. It indicated that anthocyanin protected photosynthesis apparatus in the stress environment.