Abstract: Methodology of QTL mapping for ordinal traits of disease resistance basing on the framework of a generalized linear model (GLM) was present in the paper. The location and effect parameters of putative QTL were estimated using Maximum Likelihood method. The efficiency and power were compared with the linear model (LM). The factors of influencing QTL detection efficiency (e.g. QTL effect and heritability) were simulated in our study too. Daughter design with multiple families was applied, and the number of segregating population is 500. The results showed that threshold model have a great advantage in location estimation and power of QTL mapping, and have nice efficiency and accuracy for ordinal traits. In addition, the accuracy of QTL mapping depended on the effect of putative quantitative trait loci and the value of heritability. With the increase of QTL effect and heritability, the accuracy of QTL mapping improved slightly.