A spherical CuO-Bi₂O₃-MgO/SiO₂ catalyst was prepared using the coprecipitation-gel method. The study investigated the influence of the MgO/SiO₂ ratio on the catalyst structure and the activity of the catalyst in the preparation of 1,4-butanediol from formaldehyde acetylenation. The activity and filtration performance of the catalyst were compared with commercial samples. The study found that different MgO/SiO₂ ratios not only changed the size of CuO particles, the orientation of crystal faces, the specific surface area, and the pore distribution in the catalyst, but also adjusted the interaction between CuO and SiO₂. In addition, different MgO/SiO₂ ratios could significantly alter the structure of the catalyst and enhance its activity, with the highest activity achieved when the MgO/SiO₂ ratio was 1:3. Experimental results showed that the spherical CuO-Bi₂O₃-MgO/SiO₂ catalyst in this study achieved a selectivity of 96.3% and a conversion rate of 94.0% when reacting with formaldehyde at a concentration of 38 wt% for 12 h. The catalyst outperformed commercial samples in terms of activity and had the same strength level and better filtration separation performance as commercial samples.