Abstract: Polymer of methyl-di-phenylacetylene-silane (MDPES) possesses excellent properties of high temperature-resistance, low dielectric dissipation fraction, etc, but its mechanical property is not significant for its poor bonding with glass-fiber. The di-N-m-acetylene-phenylphthalimide-ether(DAIE) was added into MDPES to modify its properties through copolymerization. To research copolymerization of DAIE and MDPES at different mass ratios, it was found that when M_DAIE/M_MDPES was 4∶5, the value of T_d5 ( temperature of 5% weight loss) is 467℃ in nitrogen; its mass residual ratio is 82.7% based on the initial mass at 800℃ in nitrogen; the flexural strength at room temperature is 274MPa; the flexural strength at 235℃ is 241MPa; the flexural strength retention at 235℃ is 88.5%; its permittivity is 4.18 and tanδ is 2.5×10^-3 in the frequency of 1MHz.