This paper focuses on an advanced layers of protection analysis (LOPA) method to assess the risk of a chemical process. Based on the chemical accident statistics between 2001 and 2014 in China, an acceptable risk function was built for chemical processes to confirm the acceptable risk value for an accident scenario. The assessment index for an emergency system was developed to assess the protective function of emergency protection based on analytic hierarchy process (AHP), and the probability of failure on demand (PFD) of emergency protection was obtained by fuzzy comprehensive assessment method and fuzzy set theory. The proposed method was applied to a methanol distillation installation. The result showed that the protections, including emergency protection, were sufficient because the probability of mitigation protection (1×10-8) was less than the acceptable risk value (3.04×10-7). The advanced LOPA method was proven to be able to improve the integrity and accuracy of traditional LOPA.