Through systematic analysis on hazardous waste landfill's (HWL) design function, the definition of Safety Life Cycle (SLC) of HWL was given with reference on the traditional definition of SLC. Base on this, the models describing the degradation process of HWL's main functional units were determined by literature reviewing and theoretical analyzing. This models were then coupled with the ERAMLL (Environmental risk assessment model for the leachate leakage) to assess the SLC for HWL. A HWL in central area in China was selected as a case study, and the result reveals that: with the aging of geomembrane and clogging of drainage system, the leakage rate of leachate in HWL will increase with time. Its environment risk will increase, and the HWL will reach to its SLC. As far as this case is concerned, its SLC is about 385a; sensitivity analysis on relevant parameters indicates that the parameter of leaching concentration has negative relation with the SLC, while the thickness of vandose and aquifer has the positive relation with the SLC. Among them, parameter that has the greatest influence on SLC is vandose thickness with the coefficient of correlation equal to 0.99, and then are the limit value of leaching concentration and aquifer thickness with the coefficient of correlation equal to -0.79 and 0.72, correspondingly. Finally, this paper suggested that more effort should be paid to strengthen the research on aging models and the factors that influence the SLC in order to consummate the theory and method of SLC assessment.