Aiming at a kind of stripe Mura problem in the production process of A type， and through the study of defective products and the statistical analysis of the data， it was found that the black matrix layer （BM） pattern in Mura abnormal area had an undercut problem. Because of the accumulation of static electricity in the contact part between the developing machine guide wheel and the glass， the contact angle between BM light resistance and glass became smaller due to the electrostatic interference， and then melt flow occurred in the BM uncured layer in the back exposure process after developing， causing the BM undercut edge after curing process. It was found that the degree of stripe Mura could be effectively improved by optimizing the back exposure process parameters and turning off the exposure lamp. Besides， the Parallel arrangement of the guide wheel was changed into Zigzag arrangement， which could furtherly improve the bad phenomenon of stripe Mura. The incidence of stripe Mura decreased from 0.8% to 0， so the improving effect was remarkable.