With good thermal properties, dielectric property and high-temperature ceramics performance, silicon-containing arylacetylene resin (PSA) has opened an attractive alternative to high performance thermosetting resins in application in the area of aircraft and missile. However, it is difficult to introduce silicon into the main chain of organic arylacetylene. In this paper, branched silicon-containing arylethyleneacetylene (BSA) resin was synthesized by methyltrichlorosilane and diethynylbenzene with zinc powder as catalyst. The advantages lie in simple operation, short reaction period and mild heat release. BSA resin exhibits excellent processability with the processing temperature of 20?C - 150?C and processing window of 130?C. The glass transition temperature of the resin casting is over 500?C. The temperature of 5% weight loss (T_d5) is up to 575?C and char yield of thermoset at 800?C (Y₈₀₀) reaches 91% under nitrogen. Also, the dielectric constant and dielectric loss of casting has no change within 10 - 10⁶ Hz.