In the present work, the dispersive stability of nano-SiO 2 with coupling agent A-174 has been investigated, then in situ nano-SiO 2 -MMA/BA/MAA copolymerization has been polymerized. Furthermore, the effects of nano-SiO 2 on performance of poly(MMA/BA/MAA)/EP have been studied, too. The results show that the nano-SiO 2 is soft agglomerate, which diameter is about 2.08 μm. But when it was oscillated by ultrasonic wave with adapt separating agent in low molecule solution, nanometer grade nano-SiO 2 particle could be attained, the average particle diameter is about 45 nm. In addition, the dispersive stability of nano-SiO 2 as treated by A-174 in polymerization system increase. As 3% of nano-SiO 2 treated by 4% of A-174 is added, the shear strength of the thermosetting acrylic–epoxy resin increase about 68%, up to 20.07 MPa, and its heat decomposition temperature increase from 332 °C to 386 °C, furthermore, the excellent water resistance and transparency have been obtained.