The physiological characters of leaf in seedling stage of 8 sugarcane genotypes were studied. The results showed that there was a very significant positive correlation (0.96) between relative growth rate (RGR) and net assimilation rate (NAR) during seedling stage. Both RGR and NAR had a negative correlation with cane juice sucrose and positive correlation with cane yield. Path analysis indicated that the NAR had directly positive contributions to cane juice sucrose and cane yield. The results showed that these physiological characters of seedling, such as higher value of NAR, LAR and chlorophyll a/b, can be used as indirect selection indices for higher yield and higher sucrose content of cane.