Abstract: In view of problem of non-ideal running effect after parallel reform of air compressor of a Plant, the second reform scheme of auto-stability pressure control system of parallel running of air compressor was introduced. The scheme makes series of gasholders of two air compressors, which not only increases capacity of gasholder but also ensures reliability and stability of flow and pressure of compressed air. It can preset interval time of cycle running of two air compressors, when one air compressor is in fault, the other can run automatically. It can directly control starting and stopping of the two air compressors through emergency stopping switch, starting and stopping switch of the two air compressors. The actual application showed that the air compressor unit by the second reform has stable and normal running.