Abstract: The photosynthetic pigment content and de novo RNA-Seq were investigated in leaf-color mutant and normal plant of Dendranthema morifolium 'Xiaguang Feiyue'. The results showed that the photosynthetic pigment content had decreased greatly of mutant plants, only about 18 percent of normal plants, but the Chl a/b observably increased in mutant plant. We generated 4.75 Gb and 4.96 Gb clean datum from the mutant and normal plant leaves using transcriptome sequencing, respectively. De novo assembly yielded 105 456 unigenes with 15 493 of length greater than 1 kb, 1 556 bp of N50. For unigenes expression analysis, we got 3 762 differentially expressed genes (DEGs), and obtained 2 741 annotations by functional annotation of the DEGs. Using GO and KEGG enrichment analyses, and qPCR verification, results indicated that forming reason of the chlorina mutant of D.morifolium 'Xiaguang Feiyue' may be expressed at low level of dmGLK2 and dmGLK1 not expressed cause chloroplast development and division blocked, chloroplast number is greatly reduced in leaf cells, thus the content of chlorophyll is overall declined. And the study will supply meaning information to the future studies on leaf-color mutants and directional breeding of D.morifolium.