Objective To investigate the application of impulse oscillation system (IOS) in occupational asthma. Methods 60 cases of patients in occupational asthma in the acute phase were chosen as research group, while 62 healthy people were arranged as control group. Both groups were relatively examined by IOS and forced pulmonary function test. All the experimental data for the tests of two groups were statistically contrasted and analyzed. Results ①Compared with control group, the research group′s data about the total respiratory impedance parameters (Zrs), resonance frequency (Fres), resistance at 5 Hz (R₅), peripheral airway resistance (R₅-R₂₀), peripheral elastic resistance (X₅) were higher, and the difference was statistically significant (P<0.05). But there was no statistically significant difference in resistance at 20 Hz (R₂₀) between the study group and the control group. ②With the comparison of the data of the forced expired volume in one second (FEV₁), percentage of the forced expired volume in one second than predicted values (FEV₁%), forced expired volume in one second to forced vital capacity ratio (FEV₁/FVC%), the differences in both groups were not statistically significant. When comparing the percentage of the forced expired flow at 25%,50%,75% of FVC than predicted values (FEF₂₅%, FEF₅₀%, FEF₇₅%) in study group and the control group,  the differences were statistically significant (P<0.05); ③ In the study group, R₅ and R₅-R₂₀were negatively correlated with FEV₁, X₅ was positively correlated with FEF₂₅% and FEF₅₀%, and there was no correlation between R₂₀ and pulmonary ventilation function. Conclusion IOS can reflect the airway resistance in patients with occupational asthma more comprehensively. It is more simple and reproducible, as well as an important supplement to the forced pulmonary function test.