In this paper,the main emphasis of the proposed discussion is on the efficiency of estimation of fixed polynomial effects in mired models based on PBIB (partially balanced incomplete block) design. We consider the condition that the design block be orthogonal in the models, and give two criteria for computing the estimator's efficiency based on three classes of estimators used in the eded design model.Lastly we show that the efficiencies of both intra-block estimator and LS estimator equal 1.