The invention discloses a light artificial pebble, which comprises a pebble core and a pebble shell that wraps the pebble core. The pebble core is mainly prepared from following components in parts byweight: 10 to 20 parts of steel slag sand, 30 to 40 parts of steel slag mud, 10 to 15 parts of cement, 25 to 35 parts of mineral powder, 5 to 10 parts of fly ash, 1 to 3 parts of an exciting agent, and 0.1 to 0.2 part of a foaming agent. The invention also discloses a preparation method of the artificial pebble. The preparation method comprises two steps: preparing the pebble core and preparing the pebble shell. Steel slag of a steel factory is taken as the main raw material to prepare the light artificial pebble, solid wastes can be effectively eliminated, the deficiency of natural pebbles is alleviated, and good environmental benefits and economic benefits are generated.