Objective To explore the characteristics of exercise ventilation function in patients with chronic duration of asthma, and the correlation of cardiopulmonary exercise test and control level and conventional lung function in patients with chronic duration of asthma. Methods Seventy-three patients with chronic duration of asthma admitted from December 2021 to December 2022 were recruited in the study. The asthma control level was assessed with the asthma control test (ACT) and the patients were divided into a well-controlled group and a poorly-controlled group. Routine pulmonary function test (PFT) and cardiopulmonary exercise test (CPET) were performed in both groups, to analyze the difference of related parameters between the two groups and observe the correlation between CPET and PFT, ACT score in the patients with chronic persistent asthma. Results CPET results showed that the VE/VCO2 slope, anaerobic threshold carbon dioxide equivalent (EqCO2@AT), and physiologically ineffective peak during exercise (VD/VTpeak) were higher in the poorly-controlled group than those in the well-controlled group (all P<0.05). The peak minute ventilation (VEpeak) and tidal volume (VTpeak) of the patients in the poorly-controlled group were lower than those in the well-controlled group (both P<0.05). The peak respiratory rate (BFpeak) and respiratory reserve (BRpeak) of the two groups were not significantly different (both P>0.05). The results of correlation analysis showed that the VE/VCO2 slope, EqCO2@AT, VD/VTpeak were negatively correlated with ACT score, and VEpeak was positively correlated with FVC%pred and MMEF%pred in the patients with chronic persistent asthma. BRpeak was positively correlated with FEV1%pred, FEV1/FVC%pred, MMEF%pred in routine pulmonary function. Multivariate logistic regression analysis showed that the increase of VE/VCO2 slope and VD/VTpeak were independent risk factors for poor asthma control (P<0.05). Conclusions Patients with poorly-controlled asthma have decreased exercise ventilatory function, mainly showing decreased ventilation and tidal volume during peak exercise and decreased ventilatory efficiency. There is some correlation between exercise ventilatory function and conventional lung function of control level in patients with chronic duration of asthma. The relevant indicators of ventilation efficiency in CPET have suggestive significance for asthma that is not well controlled, so it is necessary to carry out CPET in patients with asthma to improve the comprehensive evaluation of asthma.