Graphene and oxide graphene were prepared by optimizing Hummers and hydrazine reduction methods, then graphene/PLA and graphene oxide/PLA were prepared by the solution intercalation. The dispersion, thermal and mechanical properties were also analyzed and compared. The characterization results of graphene and graphene oxide indicated that hydrazine hydrate could reduce graphene oxide and the graphene prepared is of high purity. The characterization results of graphene/PLA and graphene oxide/PLA indicated that graphene performed better than graphene oxide in the aspects of crystallinity, crystallization rate and crystal nucleating, but graphene oxide excelled at thermal stability. The mechanical properties reduced when a small amount of graphene oxide was added. However, by adding 0.5% graphene, the tensile strength and impact strength reached the maximum.