Abstract: Using bis (tert-butylperoxy isopropyl) benzene (BIPB) as accelerant, the poly(silylene-acetylen earyleneacetylene) (PSA) was toughened by styrene-butadiene resin (SBR). The properties of the PSA toughened and modified by SBR were studied. The results show that the phase separation was easy to occur when there was no accelerant in the SBR/PSA blend system because of the difference of reaction activity between the two systems, and the addition of BIPB could make it formed a homogeneous system. With the increase of SBR content, the bending strength and modulus of PSA after modification increased first and then decreased. When the content of SBR increased to 40% (mass fraction), the bending strength and modulus of PSA after modification reached the maximum value. The fracture surface of PSA before modification was smooth, showing brittle fracture. After modification, the fracture surface of PSA obviously deepen and increased, indicating that SBR effectively improved the toughness of PSA. At the same time, with the increase of SBR content, the high-frequency dielectric properties of PSA improved.