The invention provides a copper-tin composite oxide catalyst, and a preparation method and a use thereof. The copper-tin composite oxide catalyst comprises 99.00-99.98 mass% of CuO and 0.02-1.00 mass% of SnO2, and the sum of the mass percentage contents of CuO and SnO2 is 100%. The copper-tin composite oxide catalyst has high uniformity and large specific surface area (80-100m<2>/g), and can be used in the direct process reaction for synthesizing an M2 monomer to make the M2 selectivity not lower 90.0% and the silicon powder raw material conversion rate not lower than 66.0%; and the preparation method of the copper-tin composite oxide catalyst is a wet chemical method, and has the advantages of simple operation, easy control of reaction conditions, good reappearance, low production cost, and suitableness for industrial large-batch production.