Interdisciplinary teaching is a cornerstone of modern curriculum reform, but its implementation is hindered by challenges in knowledge integration and time-consuming lesson planning. Existing tools often lack the required pedagogical and domain-specific depth.We introduce TriQuest, an AI-copilot platform designed to solve these problems. TriQuest uses large language models and knowledge graphs via an intuitive GUI to help teachers efficiently generate high-quality interdisciplinary lesson plans. Its core features include intelligent knowledge integration from various disciplines and a human-computer collaborative review process to ensure quality and innovation.In a study with 43 teachers, TriQuest increased curriculum design efficiency and improved lesson plan quality. It also significantly lowered design barriers and cognitive load. Our work presents a new paradigm for empowering teacher professional development with intelligent technologies.