Two-dimensional magnetic materials offer an ideal platform to study the fundamental research and potential applications in spintronics. However, it is still a challenging issue to raise their magnetic anisotropy energy and Curie temperature. Based on the density functional theory and the Monte Carlo method, we investigate the electron-mediated electronic structures and magnetic properties in a FeCl2/Ca2N heterostructure. It is found that a Ca2N monolayer devotes about 0.46 electrons/f.u. to a FeCl2 monolayer due to the low work function. This provides a high electron doping density of 4.28 × 1014 cm−2 and avoids the disorder effect of the traditional doping methods simultaneously such as the intercalation, adsorption, and substitution. Moreover, the magnetocrystalline anisotropy energy and Curie temperature of the FeCl2/Ca2N heterostructure enhance 66% and 100% compared with the FeCl2 monolayer, respectively. Our findings provide a practical and effective avenue to modulate the magnetic properties of two-dimensional magnetic materials.