SDG-HAZOP method is only a qualitative safety assessment.Search out the spread paths of accidents by automated reasoning through the SDG-HAZOP model without considering the probability of accidents.Although the analysis is comprehensive, systematic and complete, the analysis results are often too tedious.To address this issue, the paper raises the FTA-Based quantitative SDG-HAZOP Method.The FTA-based SDG-HAZOP method is a quantitative SDG-HAZOP method.Select the loop reactor of the polypropylene production plant as the research subject.Firstly select the key parameters.The key parameters are generally related to safety issue.The paper selects the temperature and pressure of R01.When the deviations of the two key parameters occur, it will cause danger and make the system in the non-normal state.Then add other parameter nodes and device nodes.Finally build the SDG-HAZOP model.According to the above model, select the temperature and pressure of R01 as the original analysis nodes.Assuming their values exceed the normal range, carry on the HAZOP analysis.Using the graph traversal algorithm in graph theory, search out all the compatible paths and find out all the non-normal reasons that make the key parameters in the positive deviation.Select the rise of the pressure R01 as the top event 01.According to the logical relationship between the parameter nodes in the SDG-HAZOP model, we know that P-01,P-02,P-03 and P-04 are four basic events of the top event 01.The logical symbol is "or gate" between the top event 01 and four basic events.It means that after any basic event occurs, the top event will occur.Then build the fault tree model.Select the rise of the temperature R01 as the top event 02.The steps are as above.Finally calculate the probability of accidents by using the FTA method, and then conduct the risk ranking according to the probability level.It improves the quantity of the analysis of SDG-HAZOP method.Thus it is more effective and targeted for security management.