2,7-Diphenyloxynaphthalene with large conjugated structure has been introduced into the main chain of silicon-containing arylacetylene resin and then poly(dimethylsilylene-ethynylenephenoxynaphthyloxyphenylene-ethynylene) ( m-PPNSA-MM) was synthesized. The m-PPNSA-MM resin shows good solubility and a wide processing window. A stable three-dimensional cross-linking network formed due to thermal crosslinking reactions of acetylene groups and intermolecular π–π stacking interactions after m-PPNSA-MM was cured through the process of 180°C/2 h + 220°C/2 h + 260°C/4 h. The flexural strength and modulus of the cured m-PPNSA-MM resin at room temperature are 49.2 MPa and 2.75 GPa, respectively. The cured m-PPNSA-MM resin show high thermal stabilities, the 5% temperature of weight loss ( Td5) reaches 560°C in nitrogen.