The invention belongs to the technical field of metal materials, and discloses a high-strength and high-hardness magnesium alloy in controllable reaction with water, and a manufacturing method of a component thereof. The magnesium alloy comprises the ingredients in percentage by weight: 9.0 to 15.0 percent of Gd, 3.0 to 5.0 percent of Y, 0.4 to 1.4 percent of Cu, 0.4 to 1.2 percent of Zn, 0.05 to 1.8 percent of the total content of mixed reaction accelerating elements (MRAE) such as Si, Fe, Ni, Ga and In, the balance Mg, and less than 0.01 percent of impurity elements such as Be, Zr and Ca in total. Compared with the prior art, the component manufactured by the magnesium alloy provided by the invention has high strength and high hardness, can be in controllable reaction with the water at room temperature or during heating at the same time, and is suitable to be applied in the industrial field with the requirement on integration of rigorous structure functions such as high strength, high hardness, environmental protection and degradation.