Abstract: The harm symptom and harm degree to Chinese cabbage were studied in the soot simulating test．The results show that the Chinese cabbage has changed in biology characters，physiological function，output and quality by the influence of soot of different quantities．The critical soot quantity of distinct difference and bally distinct difference are 45．7t／km²·mon．and 65．7t／km² mon．their ranges of reduction output are l6．6％and 30．0％．The influence of soot on quality of the Chinese cabbage is distinct too．The contents of,solubility sugar are decreased by 16．7％ and 31．0％ ．and the contents of coarse protein are decreased bv l5．0％ and l5．9％．respectively.