Project-based learning (PBL) is an effective approach to develop students’ twenty-first century core literacy. The development of PBL textbooks in mathematics can contribute to the implementation of PBL and the cultivation of students’ mathematical literacy, thereby promoting the reform of classroom instruction. Relying on the New Century Mathematics (NCM) that is one of the mainstream textbooks in China, this study takes the lead in integrating mathematics PBL into the national curriculum. It combines literature analysis and expert argumentation, focusing on five key processes of mathematics PBL (include Create the real-life context; propose and split a driving task; design and implement subtasks; display and exchange the product; reflection and revision) and its design principles, thus forming a design framework, which can provide inspiration for the development of textbook materials and teaching of mathematics PBL.