Calcite is one of the most important rock-forming minerals in the earth's crust, it is a very common mineral in nature and is widely used. Metal ions, such as Mg(II), Mn(II) and Fe(II), are often introduced into calcite as defects, which have a great influence on the crystal structure, mechanical properties and electronic structure of calcite. In order to understand the mechanism of the Mg(II), Mn(II), and Fe(II) doping of calcite, first-principles calculations are used to comprehensively study the various properties of calcite doped with different ions from an atomic-scale perspective. The calculation results show that the bonding characteristics of adjacent carbonate ions and layer spacing change after Mg-, Mn-, and Fe-doping, and the influence of Fe(II) on the calcite properties is the greatest, followed by those of Mn(II) and Mg(II). The influence of Fe(II) on the calcite properties is related to the ion radius and distribution of extra nuclear electrons. The elastic modulus of doped calcite decreases substantially, but the hardness of the material increases. The distribution of the density of states, energy band structure, and electrical conductivity of calcite doped with different ions also change significantly, which result in a variation in the electrical properties of calcite.