This study identified a pale-green leaf（ pgl） mutant in F8 generation of clustered-spikelet rice crossed with Japonica rice Nipponbare. The pgl mutant with the pale-green leaf at all the growth stages， represented significant reduction on plant height， flag leaf width， number of seeds per main pancile and 1000-grain weight when compared with its wild type. The content of chlorophyll（ Chl） b in pgl mutant is 0.002 to 0.003 mg/g， significantly lower than that in its wild type. The net photosynthetic rate of pgl mutant was the same as that of wild type plant at both tillering and full-heading stages. The ultrastructure analysis showed that the number of grana lamella of thylakoids in the pgl mutant were less than those in the wild type plant. The genetic analysis of the pgl mutant revealed one single recessive nuclear gene underlying the pigment phenotype. By whole-genome SNP-chip analysis using two bulks derived from the pale-green leaf plants and wild type plants in F2 segregating population respectively， pgl was located in the physical interval of 22806614 to 23000408 bp on the long arm of chromosome 10， linked with one SNP marker R1022900951CA， where the gene chlorophyll a oxygenase（ CAO1， LOC_Os10g41780） responsible for the synthesis of pigment is found. The allelism test between pgl and three pale-green mutants（ W1， Y406 and Y45） proved an allelic nature between pgl and mutant W1. DNA sequence of CAO1 revealed one base pair deletion（ T in 2507） and a T to C substitution in 3136 in pgl mutant， which results in a R to W substitution in the 9th exon. Collectively， this study provides new pale-green leaf mutants， which might be valuable in rice breeding and in the analysis of photosynthetic efficiency.