In order to clarify the specific regulation mechanism of TaCO91A gene in wheat growth and development, this study successfully obtained the orthologous gene TaCO9 of the barley (Hordeum vulgare) photoperiod gene HvCO9 in wheat (Triticum aestivum) by homologous cloning． Bioinformatic analysis, subcellular localization, transcriptional activation, and expression pattern analysis were performed． Arabidopsis was transformed by Agrobacterium infection, and phenotypic analysis was performed on the overexpressing lines． The results showed that: (1) TaCO9 contained 2 exons and 1 intron, the whole length of CDS was 876 bp, 291 amino acids were encoded, and the protein sequence contained a unique CCT domain, which was highly conserved among different species． (2) Bioinformatic analysis showed that the molecular weight of the protein encoded by this gene was about 30．7 kD and the pI was 6．24． The prokaryotic expression results showed that the molecular weight of the protein was basically consistent with the predicted results under IPTG induction; The promoter region of TaCO9 contained many cisacting elements such as light response, hormone response and stress response. (3) Subcellular localization and transcriptional activity analysis showed that TaCO9 was mainly located in the nucleus, and TaCO9 had transcriptional activation activity． (4) The results of qRTPCR showed that TaCO9 gene was expressed in all tissues, with the highest expression in leaves; TaCO9 expression level under 14 h light was significantly higher than that under 10 and 12 h light; and TaCO9 expression level in ovary and grain of ‘Xinong817’was significantly higher than that under ‘Chinese Spring’． (5) Three transgenic lines were obtained by hygromycin screening; Functional identification showed that the flowering period of transgenic Arabidopsis plants with overexpression of TaCO9 was later than that of wildtype control plants (3-4 d), and the seeds and siliques were larger．