In the process of Electrochemical micromachining (EMM), the machining gap between tool cathode and workpiece anode is the root cause leading to the error, EMM error of Micro-hole array can be divided into duplication error and repeated error. According to the characteristics of EMM, the impact factors of micro-hole array duplication error and repeated error are analyzed. The distribution of electric field strength and scattered erosion are the most important causation resulting in duplication error. There is stray electric-field existing on electrode side, making scattered erosion to workpiece, impacting micro-hole forming processing precision, the extent of scattered erosion becomes serious with processing time growing, that is showed as phenomenon of sharp corner turning round and the phenomenon is observed carefully by experiments. While the accumulation of air bubbles in the processing region leads to the emergence of repeated error. Through theoretical and experimental analysis, measures are taked to improve machining accuracy.