<p>This study is part of a larger research project that developed the New Century Mathematics (NCM) textbook series for primary grades over the last 30 years. The study explored how a series of mathematics textbooks for the primary grades was developed based on systematic evidence. The Participatory Action Research (PAR) used in this study employed triangulation and adopted narrative inquiry and documentary research approaches. The researchers participated in the development of the NCM textbook series both as observers and researchers, as well as textbook editors. Data sources included 15 transcriptions, 21 articles, and seven working papers. Analysis revealed three unique features inherent in the evidence-based textbook development pattern. These are, namely, the zone of negotiation, a complete textbook writing and revision process, and a validity verification system. Through this review of the development of the NCM textbook series, this study provides a critical analysis of contemporary methods and issues related to textbook development in China, and it presents an evidence-based textbook development pattern that may provide inspiration for the mathematics textbook research field.</p>