Abstract: The chalcone synthase (CHS) gene superfamily, also known as plant-specific type III polyketide synthase gene superfamily, encodes many important enzymes that can catalyze and synthesize various plant secondary metabolites with diverse structures and different biological activities. These metabolites play key roles in plant growth, reproduction, and plant adaptation to the environment. To fully understand the basic evolutionary rules of the CHS gene superfamily in plants and reconstruct its evolutionary history, we performed bioinformatics analysis of CHS genes in 14 plant species with whole-genome data. We performed a BLAST search to identify the gene members of the CHS superfamily. The possible expansion mechanisms and functional divergences of the members were characterized, and the evolution- ary trend of the superfamily was explored. We identified 144 genes with expression information; all are expressed in 9 land plants but not 5 algae. Phylogenetic analysis revealed that the CHS gene superfamily had an ancient origin and complicated evolutionary history. It probably appeared in early terrestrial plants to adapt to the complex environment, then experienced lineage-specific expansions or gene loss during evolution, and finally was fixed in different plant taxa through functional divergences. In addition, evolutionary testing showed that despite diverse genetic differentiation within the CHS superfamily, the whole superfamily was still filtered by strong purifying selection and no single amino acid site within an individual gene was affected by positive selection.