The invention discloses a preparing method, material and application of a medical magnesium alloy material used for 3D printing. The magnesium alloy material comprises, by mass, 10-16wt% of Fe, 1-3wt% of Mn, 0.2-2wt% of Zn, 0.5-3wt% of Ca and the balance Mg. According to the preparing steps, the material is prepared according to the compositions and the mass; pure magnesium, pure manganese, pure zinc and pure calcium are put into a preheated crucible, a covering agent is added, and the mixed material is smelted on the atmosphere condition; after the mixed material is smelted, a magnesium iron intermediate alloy is added, after the mixed material is smelted, the mixed material is stirred uniformly, and the temperature is stabilized to range from 700 DEG C to 740 DEG C; a refining agent is added, refining is carried out for 5-30 min, the material stands for 10-30 min at the temperature of 700 DEG C-740 DEG C, surface dross is skimmed, the material is poured into a metal mould, and medical magnesium alloy base metal is obtained; and the base metal is smelted and atomized, and the medical magnesium alloy material is obtained. The medical magnesium alloy material is a multi-element degradable alloy material completely composed of biosecurity human body nutrient elements, has an excellent flame retardant property, can degrade an inner implanted material medically, has an important application potential in the 3D printing field, and has a good application prospect, and the powder shape and the particle diameter are easy to control.