Abstract: In order to investigate the effects of oscillation time on the contents of organic acids in reconstituted tobacco pulp, the organic acid contents after different oscillation durations and oscillation states were determined by ion chromatography and online solid phase extraction via direct injection. The results showed that:1) When tobacco stem pulp and coniferous and broad-leaf pulp were oscillated at 50℃ for 9 h in closed or open states, the organic acid contents in the pulp varied with the oscillation duration in a different way. The contents of formic acid, acetic acid and total organic acids peaked after 6 h in the closed state and 5 h in the open state. 2) When the pulps were oscillated in the closed state for 5-7 h, the natural fermentation gas production by microorganisms reached the maximum, which was consistent with the trend of organic acid contents in the pulp. 3) Closed oscillation extremely significantly correlated to and open oscillation significantly correlated to the trends of formic acid and acetic acid in the pulp respectively. During oscillation, formic acid content changed in an irregular trend, while acetic acid content increased slowly at first and then decreased gradually. Taking acetic acid as a parameter to monitor the characteristic components in pulp could be used to optimize the pulp residence time during pulp production.