Abstract: By theoretically supposing the male variance component be equal to the female va riance component,a new method and an approximate estimation method of heritabili ty are suggested on the basis of decomposing the expected mean squares in varian ce analysis with mixed families.Seven estimation methods of heritability are com pared by an actual estimation example.The results inlicate that the difference o f the estimation value between full-sib analysis method and the method suggested in this paper is the smallest and the standard error of estimated heritability by the latter method is the smallest among the seven methods.Also the approximat e method is effective.For all methods,the more disequilibrium of the data,the bi gger difference of the estimate value by those methods.The new method can be use d when the difference of variance components between male and female is relative ly large with full-sib analysis in actual estimation.Moreover,the new method is easily calculated because the two-way classifi-cation data was analyzed by one-w ay classification variance analysis and the average relation-ship coefficient am ong mixed families may not need to be calculated.

Key words: Mixed family, Estimation of genetic parameters, Variance analysis