The invention provides a preparation method of a highly-dispersed precious metal electrocatalyst with high stability and a low load capacity. According to the preparation method, low content preciousmetals such as platinum, palladium, ruthenium, iridium, and the like, are taken as the catalytic active components; cheap metals such as iron, tin, cobalt, nickel, copper, and the like, are taken as sacrificial metals; alloy particles are synthesized through a hydrothermal method, an alcohol reduction method, or a hydrazine reduction method; then alloy particles are loaded on a heteroatom doped functionalized carbon carrier through the anchoring effect of the functionalized carbon carrier so as to obtain a catalyst precursor; then the catalyst precursor is soaked in an acid to dissolve the sacrificial metals, the alloy particles are cracked, the precious metals are left on the heteroatom doped functionalized carbon carrier, and the precious metal catalyst with a highly dispersed structureis obtained. The precious metal catalyst has an excellent catalytic performance, moreover, the loading amount of precious metals is greatly reduced, the utilization rate of precious metals is largelyincreased, the catalyst cost is effectively reduced, and the contradiction between the performance and cost is solved.