When a superconducting strip is subjected to mechanical loading, the critical current density will change. In this paper, the geometrical approach is presented to analyze strain effect on the critical current density. Based on experimental results for critical current density with the strain and magnetic field in the superconducting strip, a modified semiempirical Kim model is proposed. Then, by means of the modified model, results for superconducting strip and cylinder under pure bending are obtained numerically. The results show that, as bending moment or uniform strain is applied, the critical current density will decrease monotonically. The higher the magnetic field, the more remarkable the reduction of the critical current density. In addition, current density distribution will also vary. As a bending moment is applied, the position where the maximum current density is located will move from the left edge to the middle of the strip. On the contrary, the change of the magnetic field with bending moment is negligible.