Purpose: Due to the rapid development of the E-commerce, especially the Business-to -Customer (B2C) E-commerce, increasing attentions are paid on the logistics service quality that plays an important role. This paper aims to report a study of the key factors of logistics service in B2C E-commerce in China. We investigate the logistics process in B2C E-commerce in detail, from the e-business corporations to logistics service providers, and finally to the customers, and then identify the key factors that affect the logistics service quality. Methodology: The grounded theory approach was used to analyse the information from E-business corporations, logistics service providers, and customers, resulting in the identification of the attributes required for a high quality logistics service. Findings: Six key factors of logistics service are identified as having potential influences on logistics service perception, which include service philosophy, logistics facility design, transportation management, pricing strategy, terminal logistics service modes, and information management. Originality: This study identifies six key factors based on the first hand qualitative data, rather than from the existing service model in the literatures, which will be more useful to capture and illustrate the logistics service quality. The analysis results will provide guidance on how to improve their service quality for the B2C E-commerce to managers in logistics industry in China.