With the improvement of the quality of life, large-size, high-refresh frequency, and high-resolution display devices are becoming more and more popular. However, high-spec products are also accompanied by more display problems, and vertical crosstalk is one of them. One of the cause of vertical crosstalk is mainly due to the coupling capacitor Cpd between the data line and the pixel electrode, another cause is the leakage current when the TFT is turned off (Ioff). The great reduction in storage capacitance (Cst) and increase in line density of high-resolution products (8 K) result in serious vertical crosstalk. This paper simulates the influence factor of Cpd through software, and also determine the influence of Cpd based on the phenomenon of the samples with different pixel electrodes 2ITO overlap. At the same time, the best storage capacitance and leakage current conditions are determined by changing various process parameters; with the optimum storage capacitor and leakage current process parameters, the matching 2ITO overlap is also discussed. With all the optimal process parameters, the defect ratio drops from the initial 55.6% to 4.2%, and the image quality is greatly improved.