STR, short trandem repeats, is well known as a type of powerful genetic marker and widely used in studying human population genetics. Compared with the conventional genetic markers, the mutation rate of STR is higher. Additionally, the mutations of STR loci do not lead to genetic inconsistencies between the genotypes of parents and children; therefore, the analysis of STR mutation is more suited to assess the population mutation. In this study, we focused on 15 autosomal STR loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818, FGA). DNA samples from a total of 42416 unrelated healthy individuals (19037 trios) from the population of Mainland China collected between Jan 2012 and May 2014 were successfully investigated. In our study, the allele frequencies, paternal mutation rates, maternal mutation rates and average mutation rates were detected in the 15 STR loci. Furthermore, we also investigated the relationship between paternal ages, maternal ages, pregnant time, area and average mutation rate. We found that paternal mutation rate is higher than maternal mutation rate and the paternal, maternal, and average mutation rates have a positive correlation with paternal ages, maternal ages and times respectively. Additionally, the average mutation rates of coastal areas are higher than that of inland areas. Overall, these results suggest that the 15 autosomal STR loci can provide highly informative polymorphic data for population genetic assessment in Mainland China, as well as confirm and extend the application of STR analysis in population genetics.