Abstract: Most coal-bearing gas reservoirs in China are densely packed with overlapping layers.Single-layer development is difficult and its economic benefits are not significant.Thus, it is necessary to develop the technology for coal gas.From the perspective of co-mining, a co-mining technology is divided into the same pressure co-mining system and the sub-pressure co-mining system with two types of wells.This paper summarizes and classifies the common wellbore partial pressure technology commonly used in oil and gas field, and classifies the current partial pressure co-extraction technology from the different aspects of the oil pump, downhole string and discharge mode, and provides its characteristics and its applicability in the development of coal-bearing gas.By comparing the characteristics of these technologies and combining the characteristics of coal-bearing gas, the existing problems of coal mining gas system will be brought forward.The paper provides the direction of pressure system construction and the optimization of the product fluid channel, and also gives the problems that need attention in the design of coal column gas extraction.