Abstract: The research was conducted to study on the Bayesian strategy for mapping QTL of ratio traits. The ratio trait was defined as a ratio of two regular quantitative traits with normal distribution, which was distinguished from regular quantitative traits in the genetic analysis because it did not follow the normal distribution. A Bayesian mapping strategy was developed for ratio trait based on the maximum likelihood method using a special linear combination of the two component traits. The two component traits were analyzed by Bayesian shrinkage method, and then a new posterior sample of genetic effects was generated for a ratio trait from ones of population means and genetic effects for the two component traits, finally, QTL for the ratio trait was infered via post MCMC analysis for the new posterior sample. Simulations analysis demonstrated that the new method had higher detecting power for the QTL than maximum likelihood method.