The MADS-box gene family is a large family of transcription factors, and its members are widely distributed in the plant kingdom. Members of this family are well known to be crucial regulators of many biological processes and environmental responses. In this study, bioinformatics methods were employed to analyze the MADS-box gene family members in the common oat, focusing on their phylogenetic relationships, gene structures, conserved motifs, evolutionary relationships, promoter analysis and responses to photoperiod and abiotic stress. A total of 175 MADS-box genes were detected in Avena sativa, which were categorized into Type I and Type II. Type II members exhibited more complex gene structures, while each subfamily showed similar gene structures and motifs. Evolutionary analysis identified 138 segmental duplication events and revealed strong syntenic conservation with Triticum aestivum (337 collinear gene pairs). Four categories of cis-elements were detected in the promoter regions of the AsMADS-box genes. qRT-PCR analysis revealed that the expression of six Type II AsMADS-box genes varied in response to ABA, GA, drought and salt. Furthermore, 23 AsMADS-box members were potentially associated with heading date when the common oat plants were exposed to different photoperiod conditions. The overexpression of chr4D_AsMADS95 in Arabidopsis thaliana led to early flowering under long-day and short-day photoperiod conditions, likely associated with a significant increase in the expression levels of flowering-related genes in transgenic plants. These findings will provide useful information for future studies on stress responses and increase our understanding of the network that regulates flowering in the common oat.