In simulation of battlefield visualization, the modeling of terrain can affect the simulation effect directly, so focusing on the 3D terrain modeling should be emphasized. In this paper, technique of 3D terrain modeling and optimizing is discussed in detail, and so is the normal steps of modeling of 3D terrain with Multigen Creator. Especially how to obtain and preprocess the original data, and the main algorithms to modeling 3D terrain in Multigen Creator, and some significant techniques in 3D terrain modeling. Finally, one exquisite and intuitionistic terrain model is created in Multigen Creator.