Dynamical behavior of the liquid crystal director on the slit of the patterned vertical alignment liquid crystal cell are very unstable because there is a strong competition of strain energy of liquid crystal director. In this paper, we proved a unit patterned vertical alignment cell with stable dynamic behaviors by using the defect trap structure experimentally. In addition, we also inspected electro-optical instability of the proposed patterned vertical alignment liquid crystal cell as functions of a width and a length of the slit pattern. As a result, we could optimize the slit pattern of the patterned vertical alignment liquid crystal cell with the defect trap.