Background: This study examined the developmental relationship between Chinese children's compounding awareness and vocabulary knowledge following a 4-year longitudinal design. Methods: A test battery that included measures of vocabulary knowledge, compounding awareness, nonverbal IQ, phonological awareness, rapid automatized naming, orthographic awareness and word reading was administered to 142 Chinese-speaking students in Grade 3 (T1). In addition, vocabulary knowledge and compounding awareness were followed in Grades 4 (T2) and 6 (T3). Results: Controlling for nonverbal IQ, phonological awareness, rapid automatized naming, orthographic awareness and word reading at the initial level, the structural equation modeling results showed that children's compounding awareness made a significant direct contribution to vocabulary knowledge from T1 to T2. Children's vocabulary knowledge at T1 predicted compounding awareness at T2. However, the paths from vocabulary knowledge at T2 to compounding awareness at T3, and compounding awareness at T2 to vocabulary knowledge at T3, respectively, were not significant. The results suggest a reciprocal relationship between children's compounding awareness and vocabulary knowledge from Grades 3 to 4 in Chinese. Conclusions: These findings indicate the developmental bootstrapping relationship between Chinese students' compounding awareness and vocabulary acquisition in the middle stages of primary school.