The invention provides a catalyst for preparing N-formyl morpholine, comprising the following components in content: (A) 20-85 percent of molecular sieve; (B) 1-79 percent of carrier; and (C) 1-14 percent of binder, wherein the molecular sieve is Y-type molecular sieve or ZSM-5 molecular sieve; in the Y-type molecular sieve, the ratio of SiO2 to Al2O3 is 1-5; the ZSM-5 molecular sieve is a hydrogenous molecular sieve or a molecular sieve modified by modification elements including phosphorus and sulphur, wherein the content of the modification elements of phosphorus and sulphur is 0.1-5wt%; the carrier is Al2O3; and the binder is one or a mixture of pseudo-boehmite or hydroxyl aluminum chloride sol, silica-aluminum sol and aluminium phosphate sol. The ratio of SiO2 to Al2O3 for the modified ZSM-5 molecular sieve is 20-500, and a restricted index is 1-2. By using the catalyst of the invention, the yield and the purity of the product are high, the problem on the separation of the catalyst and a reactant does not exist, and product quality is improved beneficially.