The invention discloses a synthesis and an application for a six-nuclear ruthenium NNN complex. The six-nuclear ruthenium metal complex with high catalytic activity is synthesized by a reaction of a coordination-unsaturated ruthenium metal complex used as a raw material and a nitrogen-containing sexadentate ligand under the condition of a room temperature. The six-nuclear ruthenium metal complex provided by the invention can be applied to a hydrogen transfer reaction, and a simple, convenient and environment-friendly method for preparation of secondary alcohol is achieved.