数量性状基因座（英语：Quantitative trait loci，简称为QTLs）是一段含主控或联系数量性状的基因的DNA。可通过如AFLP或更常见的SNP等分子标签将这些控制数量性状的基因定位到基因组的特定区域上。这是对主控性状变异的实际基因进行鉴定与测序的先行步骤。数量性状指的是那些可区分程度的表型（特征），这些性状起因于多基因效应（即由两个及以上的基因共同控制）及环境的共同作用。

A quantitative trait locus (QTL) is a section of DNA (the locus) that correlates with variation in a phenotype (the quantitative trait). The QTL typically is linked to, or contains, the genes that control that phenotype. QTLs are mapped by identifying which molecular markers (such as SNPs or AFLPs) correlate with an observed trait. This is often an early step in identifying and sequencing the actual genes that cause the trait variation.