Graphite oxide （GTO） and graphene oxide （GO） were prepared from two graphite raw materials with two particle sizes using three wet chemical methods.The obtained different GTO and GO were qualitatively analyzed by XRD，IR，and SEM and TEM characterization in terms of layer spacing，surface functional groups，structural integrity，and microscopic morphology，etc.Meanwhile，the concept of D-peak origin in Raman characterization was introduced，and the degree of defects introduced into the graphite structure during the chemical reaction，which was the proportion of oxygen-containing functional groups on the surface，was analyzed semi-quantitatively based on the I_D/I_G ratios of different samples.The results show that graphene oxide with different functional group states and properties can be obtained by controlling the synthesis method and graphite particle size.The degree of oxidation of graphite by chemical methods is in the order of：HydrothermalHummers≈ Staudmaier.The smaller the size of the graphite raw material，the more rapid and pronounced the oxidation process becomes.