In order to analyze quantitative characters effectively, a gene (effective factor) model is established, which can describe the phenotypic distribution of a quantitative character in the segregating population quite well because it has not only involved the additive effect of genes, but has also considered the dominance deviation and epistatic deviation. In this paper, we also present a method to estimate the parameters of the model. Based on the results of some illustration, the proposed model is considered to be superior to Castle-Wright's formula, and it may provide more useful information to breeders.