The invention discloses a preparation method of an oxidized grapheme/titanium dioxide photocatalytic composite material precursor. The preparation method includes the steps of S1) , preparation of an oxidized grapheme/tetrabutyl titanate composite material; S2), preparation of an oxidized grapheme/titanium dioxide composite material. With the preparation method, the photocatalytic composite material precursor with uniform load of titanium dioxide can be prepared; TiO2 in the precursor and the oxidized grapheme are organically composited, TiO2 particles are evenly loaded on slice layers of the oxidized grapheme, introduction of the oxidized grapheme has double functions of loading the TiO2 particles and improving photocatalytic activity of titanium dioxide, and photodegradation efficiency is effectively improved; the material for the precursor has good coating function; the preparation method has the advantages of simple steps, easiness in operation, moderate preparation conditions and easy control, high efficiency and the like.