In the reserve model of B-F, in order to make the estimated reserve of the accident year mean independent of the specific form of prior distribution, the credibility method is adopted. On the basis of \ncite{10} model, considering the relationship between the amount of claims in different years of progress in the same accident year, the optimal non-homogeneous and homogeneous credibility estimates of the accident year means are obtained under the balanced loss function. When \omega=0, the result is consistent with that of the original model, and the original model is generalized.