Abstract: AlN and BN were modified with silane coupling agent KH570 under anhydrous conditions, and then were used as thermal conductive fillers added into glass fiber reinforced styrene-butadiene resin composites. The effect of different thermal conductive fillers on the water absorption, thermal conductivity, dielectric properties and mechanical properties of the composite was studied. The results show that filling the two thermal conductive fillers could improve the water absorption of the composite; comparing with the unmodified filler, the filling of the modified filler had a small increase in water absorption of the composite. With the increase of modified AlN content, the dielectric constant and dielectric loss of the composite increased significantly, indicating the dielectric properties decreased, and the flexural strength increased first and then decreased. With the increase of modified BN content, the dielectric constant of the composite increased, the dielectric loss decreased, and the flexural strength increased. The two modified thermal conductive fillers could improve the thermal conductivity of the composite. Compared with single component filling, modified AlN and modified BN hybrid filling had a stronger effect on improving the thermal conductivity of the composite.