The invention relates to magnesia-calcium clinker adopting the core-shell coated structure and a preparation method of the magnesia-calcium clinker. According to the technical scheme, dolomite ore is crushed to 5-8 mm, subjected to heat treatment at the temperature of 900-1,000 DEG C for 0.5-1 h and ball-milled to have the particle size smaller than 80 mu m, and light-burned fine dolomite powder is obtained; then the light-burned fine dolomite powder and water are blended in the mass ratio being 100:(35-40) and mixed in a disk granulating machine for 0.2-0.3 h for granulating formation; formed particles are immersed in Cu(OH)2 gel for 1-2 min, and dolomite particles adopting the coated structure are obtained; then the dolomite particles adopting the coated structure are dried at the temperature of 30-35 DEG C for 12-15 h, dried at the temperature of 110-120 DEG C for 6-12 h, heated to the temperature of 1,200-1,400 DEG C in a resistance furnace, kept at the temperature for 2-3 h and cooled with the furnace, and the magnesia-calcium clinker adopting the core-shell coated structure is obtained. The magnesia-calcium clinker adopting the core-shell coated structure and the preparation method of the magnesia-calcium clinker have the characteristics that the production cost is low, the preparation technology is simple and the energy consumption is low, the prepared magnesia-calcium clinker adopting the core-shell coated structure has the complete core-shell coated structure and the excellent hydration resistance.