This paper aims to improve the topic guidance performance of a large-scale language model (LLM)-based dialogue system. To address the lack of conceptual identification in existing methods, which are characterized by user confusion (__T60324_____), we propose the Ask-Good-Question (AGQ) framework, which utilizes an improved Concept-Enhanced Item Response Theory (CEIRT) model. AGQ combines the CEIRT model and LLM to assess the user's knowledge level and generate guidance questions to efficiently retrieve relevant information. Experimental results show that the proposed method improves the user's information retrieval experience compared to existing methods.