The present invention provides the cloning of intron-containing Amaranthus caudatus agglutinin (ACA) gene from Amaranthus caudatus and the coding region gene sequence encoding the ACA protein. The said gene sequence of the ACA gene coding region was ligated with highly efficient and stable microbial expression vectors to produce the ACA protein using microbe largely. High expression of the ACA gene can make the transgenic plants have antiaphid activity and improve the nutrition quality thereof. The ACA gene has potential application value in plant anti-insect gene engineering and quality improvement.