Taking the process piping and piping instrumentation diagram (P&ID) of gas fractionation unit design phase as the main basis, application process of HAZOP analysis along with risk matrix were discussed. According to the results of HAZOP analysis, the risks that exist in  safety management of gas fractionation unit design phase were recognized effectively. The measures to reduce the risks were proposed, and based on the situation of applying HAZOP analysis in practice, the attention matters in its application process were also proposed.