The aim of this study is to assess the medium to long-term effect of acute irritant gas poisoning on cardiopulmonary exercise function in patients after clinical cure. Fourteen patients after an average of 18.5 months of clinical cure of acute irritant gas poisoning were recruited, and 14 healthy individuals were selected as control. All subjects were examined by resting pulmonary function testing (RPFT), cardiopulmonary exercise testing (CPET), and arterial blood gas (ABG) analysis. No statistically significant differences were found between poisoning and control groups for baseline parameters (age, height, and weight) or ABG values (pH, PaO2, PaCO2, and SaO2) (P > 0.05). For most RPFT parameters, including FEV1/FVC, FEV1, FEV1%pred, RV/TLC, DLCO%, and FVC%, no statistically significant differences were observed between poisoning and control groups (P > 0.05). However, MVV% was significantly lower in poisoning group compared with healthy individuals (P < 0.05). Statistically significant differences were observed for some CPET parameters, including peak VO2, peak VO2/kg, peak VE, and lowest VE/VCO2 (P < 0.05), and peak load, V D/V T, and peak PETCO2 (P < 0.01) between the two groups. However, there were no statistically significant differences in peak VO2%pred or peak O2 pulse between poisoning and control groups (P > 0.05). Compared with controls, patients with acute irritant gas poisoning had decreased cardiopulmonary exercise capacity and ventilation effectiveness after clinical cure.