The present application provides a heterojunction nano material, a negative pole piece of a lithium ion battery, and a lithium ion battery, where the heterojunction nano material includes a MoO3 nanobelt and a metal oxide in the alloy lithium intercalation mechanism coated on the surface of the MoO3 nanobelt. The negative pole piece of the lithium ion battery uses the heterojunction nano material as an active material, and the lithium ion battery using the negative pole piece of the lithium ion battery has a large reversible specific capacity and a high cycle stability.