This study seeks to verify improvements of the stair stepping exercise training on cardiopulmonary fitness condition and sleep condition in patients with obstructive sleep apnea syndrome (OSAS). The quasi-experimental, two group repeated-measures study design was used. Patients meet the following criteria were invited to participate in this study: being diagnosed with AHI (Apnea-hypopnea index)>15/hr and ODI (oxygen desaturation index)>10/hr by Polysomnography, aged 19 or older. Eighteen patients with OSAS treated in the outpatient department of Chest Medicine were recruited, included study group and control group .The study group patients performed stair stepping exercise training daily for eight weeks at home. Outcome measures included cardiorespiratory fitness condition assessed by the 3-Minute YMCA Step Test, in which including physical fitness index and gross oxygen consumption (VO2), and sleep condition assessed by Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, and Polysomnography. Data were recorded just prior to the stair stepping exercise at Day 1 as baseline, at the end of the fourth week, and at the end of the eighth week. Results of this study showed, physical fitness index, Epworth Sleepiness Scale , AHI, Pittsburgh Sleep Quality Index and symptom scale-snoring were significantly improved. Differences in the effect of stair stepping exercise for other outcome variables were either minimal or not statistically significant. Eight weeks of stair stepping exercise training could be useful in increasing cardiorespiratory fitness condition and improving sleep condition on patients with OSAS.