The invention discloses a method for smelting ferro-molybdenum from ammonia leaching residue to recover molybdenum. The method comprises the following steps: 1, the ammonia leaching residue and an auxiliary material are added into a mixer to be mixed uniformly to obtain a mixture, wherein the auxiliary material comprises ferro-silicon, ferro-phosphorus, aluminum particles, sodium nitrate and a fluxing agent, and the fluxing agent adopts calcium oxide or fluorite; 2, the mixture is loaded in a smelting furnace, the surface of the mixture is covered with a layer of firelighter, and a reaction product is obtained after ignition for smelting; the reaction product stands still so that iron is precipitated to form smelting residue and a ferro-molybdenum ingot, the smelting residue is removed, the ferro-molybdenum ingot cools naturally to be solidified, and the purpose of smelting ferro-molybdenum from the ammonia leaching residue to recover molybdenum is achieved. According to the method provided by the invention, the ammonia leaching residue is mixed with the smelting auxiliary material on the basis of a silicon-aluminium thermal reduction method, and the smelting residue and the ferro-molybdenum ingot are produced by a ferro-alloy self-heating reaction technique, so that the effect of recycling molybdenum metal is achieved; when used for smelting ferro-molybdenum to recover molybdenum in ammonia leaching residue, the method has the advantages of high resource utilization rate, low smelting auxiliary material consumption, small environmental pollution and high metal recovery rate.