COA technology used in ADS mode LCDs is analyzed through theoretical method and basic experimental verification. Compared to IPS and VA mode LCDs, more films on R/G/B will cause the special process manufacturing issues for ADS mode LCDs. It mainly presents in three problems, which are process compatibility, flatness and deep-hole process. In this paper, the risk points of COA technology are put forward, and the possible solution is also analyzed.