Background: Both obstructive sleep apnea-hypopnea syndrome (OSAHS) and obesity are related to cognitive deficits, but the interaction effects of OSAHS and abdominal obesity on cognitive function are unclear. Thus, we performed this study to investigate this issue. Methods: We recruited subjects who received polysomnography test, anthropometric measurements and cognitive function assessment and/or blood protein test. Correlations between apnea-hypopnea index (AHI) and cognitive function were assessed. Analysis of covariance was used to compare the differences in cognitive function between groups and detect the interactions of OSAHS and obesity on cognitive function. Multiple linear regression models were used to determine the associations between OSAHS and cognitive function. Results: In total, 196 subjects with Montreal Cognitive Assessment (MoCA), 161 subjects with Symbol Digit Modalities Test (SDMT) and Trail making test, and 44 subjects with blood protein test were enrolled. Significant negative correlations between AHI and visuo-spatial and executive, language, delayed recall and total score of MoCA were observed. After adjusting for multiple confounding factors, subjects with severe OSAHS had significant lower delayed recall score and total score of MoCA, SDMT index, and A\beta40 protein level than those with non-severe OSAHS group. Severe OSAHS was independently negatively associated with delayed recall score and total score of MoCA, SDMT index, and A\beta40 protein level. An interactive effect of severe OSAHS and abdominal obesity on language score of MoCA was found. Conclusions: Severe OSAHS increased the risk of cognitive deficits. Interaction effect of severe OSAHS and abdominal obesity on language was seen.