The objectives of this research were to develop and design an automated workflow using n8n combined with an AI Agent for a sales Q&A system, and to evaluate system efficiency and user satisfaction. The developed system applies Large Language Model (LLM) technology working with a Knowledge Base through the Retrieval-Augmented Generation (RAG) process. n8n is utilized as a workflow orchestrator to connect the LINE application with the AI processing unit. The results indicated that the n8n workflow design effectively enabled the system to transmit messages and retrieve product information to answer customer inquiries accurately, rapidly, and naturally, replacing repetitive human tasks. The user satisfaction assessment showed a high level of satisfaction, demonstrating that the system can be effectively applied to real-world sales operations.