Graphene oxide/NaYF4: Yb, Er nanocomposites have been synthesized via hydrothermal synthesis, in which spherical cubic phase NaYF4: Yb, Er nanocrystals with uniformity are implanted onto the surface of graphene oxide (GO). Using a near infrared laser set to 980 nm, the light-to-heat energy transfer efficiency of GO/NaYF4: Yb, Er is 13.9% higher than GO by itself, revealing that the photothermal conversion efficiency of GO could be enhanced by doping NaYF4: Yb, Er nanocrystals. This phenomenon can be attributed to the energy transfer between the NaYF4: Yb, Er nanocrystals to the energy receptor in the GO substrate.