The prepare graphene oxide/polyhdral oligosilsesquioxanes （GO/POSS_C-I） composite was prepared by the in-situ method under acid and miscellaneous conditions. SEM， XRD and IR were performed to characterize morphologies and crystallizations of as-prepared material. The results show that considerable inorganic-organic hybrid POSS nano-material with shell-core structure is inserted into the surfaces of well dispersed lamllar GO. In the curing process of modified bismaleimide（BMI） resin， GO/POSS_C-I composite material is well dispersed in the matrix of resin to form homogeneous black cured compound resin. Results of DMA tests show that GO/POSS_C-I composite material has obvious restriction effect on the movement of organic carbon chains and improve the thermal stability of material.The optimum glass transition temperature is 27℃ higher than that of unmodified bismaleimide resin. Furthermore， the mechincal properties of composite are improved because of the crack passivation or pull-out effect of GO/POSS_C-I composite. The bending strength and modulus of modified BMI resin are incresed by 16.5% and 3.4% ，respectively.