Took cauliflower variety of Chonghua as a material, the artificial environment control experiment was conducted in Nanjing University of Information Science and Technology from August to November in 2014. The waterlogging was treated as five levels: 3, 6, 9, 12, 15 days, took normal irrigation as control (CK)，the root activity and photosynthetic parameters of cauliflower were measured. The results showed that the root activity presented a declining trend with the increase of waterlogging days. When the experiment lasted for more than 9 days, the root activity tended to 0, when the experiment lasted for 3, 6, 9, 12 and 15 days, the maximum net photosynthetic rate decreased 4.90%, 68.13%, 78.71%, 90.92% and 98.68%, respectively, meanwhile, light compensation point decreased and light saturation point increased. Stomatal conductance, transpiration rate and intercellular CO2 concentration decreased significantly under waterlogging stress, but stomatal limitation increased at the beginning of the stress, that is stomatal limitation resulted in the decrease of net photosynthetic rate at early stress. The study confirmed that all indices declined obviously during the early 6 days and then tended to stabilization, so the 6th day was the critical indicator of Chonghua cauliflower.
