A deformation model with the consideration on reaction stress between grains in polycrystalline aggregates is proposed, in order to solvethe problems of strain and stress incompatibility appearing in previous Sachs- and Taylor-type models. The corresponding simulation fortensile deformation indicates that the model predicts orientation evolutions similar to that made by Taylor assumption, while the attention toboth of the stress and strain compatibility has been given without cryptic fitting parameters. A 'hard' area, where no track of tensile directioncould run through, was predicted near <1 1 1> according to the simulation, which agrees with some experimental observations.