Based on the imbalance of gas systems for steel complex， the study indicated the reason is mainly static imbalance caused by irrational unit design in power plant. The model is implemented by probability statistics and numerical analysis method， aiming at the reflection on the imbalance of gas system in steel complex based on the statistical characteristics of residual gas. The power plant of 2.8-million-ton crude steel complex was taken as an example to designe the scheme of power generation based on the max of residual gas. The results indicated the reasonable design scheme is 90%Cmax combined the financial evaluation; the scheme can distribute the residual gas reasonably， safely and efficiently， for improving energy utilization efficiency and decreasing the production cost. Although considering environmental costs as part of the total cost increases the total business operating costs， it is very important for the environment protection and sustainable development of society.