Abstract: Taking practice of building gas drainage system at a high gassy mine as example, the paper introduced design of gas drainage pipeline system in gas drainage system, namely design of laying line of pipeline, selection of gas-suction diameter and calculation of pipeline resistance, and gave selection design of gas-suction pump according to calculating result of pipeline resistance and selection principle of gas-suction pump. The actual application showed that the coal mine has not appeared phenomenon of disallowed gas concentration with 46% gas-suction rate after using the gas drainage system.