The invention aims at providing application of a CRYBA4 gene in preparing and detecting a congenital cataract-microcornea syndrome diagnosing product. The invention provides a novel purpose of the CRYBA4 gene and further provides an effective way of carrying out congenital CCMC disease gene diagnosis, antenatal gene screening and genetic counseling. An application effect shows that a gene SNP locus and a detecting primer provided by the invention can be effectively applied to quick detection of a CRYBA4 gene mutation site on a clinic patient and fetus villus or amniotic fluid.