In this paper, the first‐principles method is used to calculate the electronic structure of the intrinsic WSe2 system and the Ca adsorbed WSe2 system under shear deformation, and the diffusion barrier of Ca on WSe2 is studied in depth. The results show that shear deformation can effectively reduce the band gap of WSe2 system, and shear deformation can easily lead to the transition from semiconductor properties to metal properties. The adsorption of Ca leads to the change of the band structure of WSe2. The contribution of Ca‐d electrons leads to an increase in the peak in the range of 3–6 eV. The shear deformation reduces the diffusion barrier of Ca on the WSe2 surface. This paper provides an improvement method for the application of WSe2 in the field of battery.