Abstract: Experiments were conducted in an open-top fumigation device. The potted wheat and vegetables were exposed to four sulfur dioxide (SO2) exposure duration of 30 minutes, 60 minutes, 90 minutes and 120 minutes in order to investigate the impact of SO2 on leaf sulfur content, leaf conductance and pH value of extracted leaf fluid. Result showed that SO2 exposure duration was strongly negatively correlated with pH value of extracted leaf fluid, but was significantly positively correlated with conductance of extracted leaf fluid and leaf sulfur content. Among leaf sulfur content, leaf conductance and pH value of extracted leaf fluid, leaf sulfur content was the most effective biophysical and chemical indexes to estimate the acute injury of crops caused by SO2. For testing the results, field experiment was laid out in a split plot design with rice varieties of Shengdao 13, Yangguang 200 and Lindao 10. Rice samples were exposed to SO2 at different concentrations inside fumigation chamber. Results showed that for three rice varieties, leaf sulfur contents increased according to the elevated SO2 exposure concentrations at the same growth stages. And compared with leaf sulfur contents of control concentration, the leaf sulfur contents exposed to different SO2 concentrations increased greatly and had significant difference with leaf sulfur contents of the control concentration.