Abstract: During the transition from open-pit to underground mining in Xiaowanggou iron mine，overburden layer for sublevel caving is formed through the induced caving process of open-pit slope.This process is effective in extending space conditions of simultaneous open-pit and underground mining，and achieving the production increase during the transition from open-pit to underground mining.The paper describes the schemes，techniques and implementation of induced caving，and analyzes the main factor of affecting the caving process.

Key words: Transition from open-pit to underground, Overburden layer, Induced caving