Existing product and service quality analysis is often based on questionnaire survey or product reviews， but there are problems such as difficulty in questionnaire collection and invalid data in product reviews. As a bridge between customers and businesses， the customer service dialogue contains rich customer opinions from product to service perspective， however， there are still few studies using customer service dialogues to analyze product and service quality. A product and service quality analysis method based on customer service dialogues was proposed， which firstly combined the product features and service blueprint to determine product and service quality evaluation factors， and used the Important?Performance Analysis （IPA） method to define the importance and performance index of evaluation factors. Then， quantitative analysis of the importance and satisfaction of products and services was performed by using the dialogue topic extraction and sentiment analysis. The method was applied on the real customer service dialogues of a Taobao flagship store which sells disinfection and sterilization products， and 18 evaluation factors were established， whose importance and performance were quantified based on more than 900 thousand real historical customer service dialogues， thereby analyzing the quality of products and services of the flagship store. Finally， a questionnaire on the professional customer service employees was carried out to verify the effectiveness of the proposed method.