The invention relates to the technical field of gypsum modification, in particular to a fabrication method and application of gypsum micro powder. Free water of ardealite is removed, then ardealite is ground till the degree of fineness reaches 600 meshes or above, the sieving rate is controlled to be 93% or above, and meanwhile an additive is added so that activity of the gypsum micro powder can be high, water resistance can be excellent, particularly it is difficult for the gypsum micro powder to absorb moisture in the air, agglomeration can be avoided, the shelf life of the gypsum micro powder can be long, and quality can be good; besides, when the gypsum micro powder is used for preparing corresponding products, fracture resistance and compression resistance are excellent, and the softening coefficient is excellent; presetting time is long, and the product preparation process is convenient to conduct.