Graphene oxide/copolymer polystyrene microspheres with surfactant used as dispersing agent were prepared by in situ suspension polymerization. The samples were characterized by SEM,XRD,FT-IR spectrometer and thermogravimetric analysis. The results show that graphene oxide not only disperses uniformly in the matrix but also absorbs the polystyrene molecular chains tightly. Moreover, due to the good dispersion state of graphene oxide and the restriction on the chains, the microspheres show greatly enhanced thermal stability, the temperature of the extrapolated onset of the nanocomposites increases by 50 ℃ with loading of 0.4% graphene oxide. However the glass transition temperature of the microspheres is only increased by 2~4 ℃ since the addition of graphene oxide would decrease the crosslinking density of the composite microspheres.