This study reports a new approach for the preparation of molybdenum (Mo) with controllable morphology by reducing molybdenum trioxide (MoO3) with ammonia (NH3). It is found that the morphology and particles size of as-prepared Mo are always remained the same as that of used MoO3 except for the high porosity, which resulted from the removal of oxygen/nitrogen. A possible reaction mechanism is proposed. This study may have an important guiding role for the preparation of different characteristics of Mo.