Decompressive craniectomy (DC) is a commonly used life-saving neurosurgical procedure but always accompanied by a severe case of temporalis damage and even adhesions with the dura mater, which may lead to irreparable serious consequences. A suitable material for repairing the damage and preventing adhesions is urgently needed. However, existing materials mostly struggle to meet the clinical demands. In this paper, we introduce a novel siloxane nanocomposite: Ag-Quercetin-Polysiloxane (AQS), to effectively avoid the irreparable serious consequences caused by the cases after DC. AQS has many excellent properties, including flexibility, hydrophobicity, recyclability, low cost, and especially the anti-inflammatory and broad-spectrum antibacterial. Comprehensive experiments were conducted to verify the critical role of AQS, demonstrating a superiority of the AQS in various aspects. In vitro experiments, AQS possessed broad-spectrum antimicrobial activity, effective anti-adhesion properties against multiple cell lines, and the slow-release profile of Ag and quercetin. In vivo experiments, AQS effectively prevented adhesions between the temporalis muscle and dura mater, reduced pro-inflammatory IL-6 secretion, increased anti-inflammatory IL-10 and pro-healing PCNA production, thereby promoted temporalis remodeling. Furthermore, AQS exhibited excellent biocompatibility both in vitro and in vivo experiments. This nanocomposite may provide a novel therapeutic strategy for addressing the repairment and adhesion problems of temporalis muscle following DC.