Increasing usage of metals in engineering structures has made the metal forming process become superior in the solid mechanic researches. Meanwhile, the physical theories are of high significance due to the individual features. The crystal plasticity theory is one of these theories. This theory predicts the texture evolution and deformation of these materials by modeling the plastic deformation mechanisms of crystal material’s micro-structure (such as metals). Connecting with micro-structure enables this theory to predict the anisotropy of single crystals, and also the prediction of some phenomena in polycrystals which are aggregate of single crystals, is possible. Presenting a suitable work hardening model which contains the anisotropy behaviors of single-crystals is very important. In this paper, at first, the principles of crystal plasticity are explained, and then by evaluating several experimental results and the most commonly used work hardening models, a new work hardening model will be presented. This model adapts better with experimental results, compared to the previous models. The scope of this research is specifically for crystal materials with FCC structure, nevertheless, some part of this research is applicable to the other structures.