Research Findings: This study investigated teachers' Concept development (CD) strategy use in whole-group math teaching and its associations with children's higher-order thinking processes in 25 Chinese preschool math lessons. We utilized the CD dimension within the Classroom Assessment Scoring System (CLASS) to guide our exploration. CD identifies 12 specific cognitive strategies, grouped into four organizing indicators, and include analysis and reasoning, creating, integration, and connections to the real world. Results showed: (1) Chinese teachers rarely used strategies such as "connecting concepts," "integrating with previous knowledge," and "real-world applications"; (2) Over half of teachers' CD strategies failed to facilitate children's higher-order thinking. When teachers used "clarification/comparison" and "brainstorming" strategies, however, was positively associated with children's displaying high-level cognitive processes. Practice or Policy: Findings shed light on the need to promote effective CD strategies during math instruction for preschoolers and have implications for teachers' professional development.