Previous studies uncover that vocabulary knowledge may be related to compound structure awareness (the awareness of relational structure embedded in compound words), and they both contribute to reading comprehension. Yet, limited studies have examined the dynamic relationship between vocabulary knowledge and compound structure awareness, or their joint contributions (including growth rates) to reading comprehension. Our study aimed to fill this gap in Chinese, an ideal target language with complex grammatical structures of compound words. We followed 125 native Mandarin-Chinese-speaking children in Mainland China from Grades 3 to 6, with one testing point in the fall of each grade and a total of four testing times. These children's vocabulary, compound structure awareness, and text reading comprehension were measured as three key variables, and their Chinese character reading, word reading fluency, and compounding awareness were measured as three control variables in model analyses; all materials were adopted from previous research and were highly reliable and valid. We fitted the latent growth models and found that children's initial vocabulary in Grade 3 significantly predicted their compound structure awareness growth over Grades 3 to 6, and then predicted reading comprehension in Grade 6. However, such results were not evident the other way around. Importantly, initial vocabulary knowledge and compound structure awareness in Grade 3 and their growth rates from Grades 3 to 6 contributed to reading comprehension skills in Grade 6. Our findings demonstrate the necessity of considering vocabulary knowledge and compound structure awareness jointly and longitudinally to support early reading development.