The advent of molecular genetic marker data paves the way for the study if detecting and locating (mapping) genes affecting quantitative traits (quantitative trait loci, QTL). In mapping QTL, the genetic properties of the gene segregation and recombination, and the quantitative trait, which is usually governed by multiple genes and affected by environments, can be well characterized by statistical principles, and statistical analyses have been played a very important role in QTL mapping. In practice, the result of QTL mapping will be applied to marker-assisted selection or gene transfer for trait improvement. Therefore, the keys to ensure an efficient trait improvement depend not only on the careful operations on the organisms in the laboratory but also on the implementation of appropriate statistical methods in data analysis. In this paper, the statistical methods for QTL mapping are introduced, reviewed and discussed.