Abstract: CO₂ hydrogenation to methanol is an important way to achieve the goal of "double carbon". In this paper, CuZnAlY catalyst was modified by adding different contents of Mg, and its effect on the performance of CO₂ hydrogenation to methanol was systematically studied. XRD, TPR, TPD and XPS were used to analyze the structure of the catalyst. The results showed that the addition of Mg built a suitable alkaline site, enhanced the CO₂ adsorption capacity, improved the CO₂ conversion and methanol selectivity. Among them, CZAYM_2.5 composite catalyst has the highest space-time yield. Under the conditions of T=250 ℃, P=3.0 MPa, GHSV=4000 mL/(mL·h), reaction gas H₂∶CO₂=3∶1 （molar ratio）, the CO₂ conversion, methanol selectivity and methanol space-time yield reached 18.95%, 51.49% and 0.1549 g/(g·h), respectively. Meanwhile, stability tests were carried out for 720 h at improved pressure P=5.0 MPa. The results showed that: the CO₂ conversion reached 22.00%, the selectivity of CH₃OH was about 63.00%, and the methanol space-time yield was about 0.2100 g/(g·h). The catalyst showed good stability.