The invention discloses a high-strength high-plasticity medical magnesium alloy, and a preparation method and applications thereof, and belongs to the technical field of medical magnesium alloy material. According to the preparation method, compound addition of Zn, Nd, and Mn as alloy elements into magnesium matrix is carried out, and magnesium alloy is subjected to extrusion, so that plastic deformation capacity of magnesium alloy is improved greatly, and tensile strength of magnesium alloy is increased greatly by increasing Zn content of the magnesium alloy. The high-strength high-plasticity medical magnesium alloy comprises, by mass, 0.2 to 6.0% of Zn, 0.5 to 2.0% of Nd, and 0.5% of Mn; weight content of limited impurities is controlled as following: Fe<0.006%, Cu<0.005%, Ni<0.006%, and the balance Mg. An alloy ingot casting is subjected to homogenization treatment at 400 to 550 DEG C for 10h, and is subjected to extrusion at 390 DEG C, wherein extrusion ratio is controlled to be 36:1, and animal oil is taken as a lubricant. Maximum room temperature tensile strength of the high-strength high-plasticity medical magnesium alloy can be 300MPa, and maximum elongation percentage can be 37%.