Abstract: The single plant grain weight is one of the key factors affecting the quinoa yield. In order to understand the genetic basis for the formation of single plant grain weight in quinoa and identify the genetic segment that controlled the variation of single plant grain weight in quinoa, this study used 120 parents separated populations constructed from two parents with significant differences in single plant grain weight as materials. Based on GBS sequencing and phenotypic identification results, the QTLs that controlled the variation of quinoa yield were identified using a complete inter region mapping method. The results showed that a total of 7 QTLs controlling single plant grain weight of quinoa were identified, namely qSPW3-1 and qSPW3-2 located on the third chromosome, qSPW4 located on the fourth chromosome, qSPW5 located on the fifth chromosome, qSPW7-1 and qSPW7-2 located on the seventh chromosome, and qSPW12 located on chromosome 12. A single QTL could explain phenotypic variations ranging from 6.09% to 10.17%, with QTL sizes ranging from 10.54 kb to 401.86 kb.