The key of processing for deephole precise hydraulic components is the technique of deephole precise processing.At present,most of the deephole precise hydraulic components are imported in China because the deep hole technique is not well developed.Through analyzing the processing of servo cylinder,high hydraulic cylinder,hydraulic rotary actuators of a company as well as the sealing mechanism and sealing failure,the importance of deephole precise processing for deephole precise hydraulic components was expounded and the processing line was figured out.