In order to utilize and estimate efficiently the decaploid accessions of Saccharum spontaneum L. and to develop the elite traits, genetic diversity index, correlation coefficient of variance, correlation among quantitative traits, and correlation between quantitative traits and altitude or latitude were evaluated based on eight qualitative traits and eight quantitative traits of 171 decaploid accessions of S. spontaneum collected from 9 regions of 6 provinces in China. The results showed that the Shannon–Wiener genetic diversity index of qualitative traits was generally low. The accessions from middle part of Yunnan exhibited the highest genetic diversity index(0.636 6), while those from the northwest showed the lowest(0.335 8). There were high genetic variances in quantitative traits, accessions from southwest of Yunnan showed the highest variance value (33.06%) and those from Guizhou showed the lowest(22.12%). Yield related traits exhibited negative correlations with elevation or latitude, sugar related traits showed negative correlations with elevation and positive correlations with latitude. Fiber was only positively related to elevation and there were positive correlations among yield related traits and among sugar related traits. Analysis of genetic structure indicated that the genetic variances of phenotypic traits derived mainly from inner sampling regions. The big gene flow(Nm>3) among populations from different sampling regions suggested no significant genetic divergence among these populations. According to genetic distance and UPGMA, phenotypic traits of decaploid accessions of S. spontaneum were related to the terrain of the sampling region to some degree. The accessions from northeast and northwest of Yunnan with high terrain were clustered into a small group, and the accessions from regions with low terrain as southeast and southwest of Yunnan, southeast regions of Sichuan and Guangdong were clustered into a big group.