The invention discloses determination method and device for an SIL (Safety Integrity Level) and a memory medium and belongs to the field of natural gas gathering and transportation safety. The methodcomprises the steps of determining at least one SIF (System Integrated Function) corresponding to EUC (Equipment under Control); determining an equipment correction coefficient and a management systemevaluation coefficient of the EUC, and a basic failure probability corresponding to each hazard factor in at least one hazard factor which influences each SIF; determining a theoretical failure probability of each SIF based on the equipment correction coefficient, the management system evaluation coefficient and at least one basic failure probability corresponding to each SIF; determining a failure consequence level of each SIF; and determining the SIL of each SIF based on the theoretical failure probability and the failure consequence level of each SIF. According to the methods the devices and the memory medium, correction quantitative solution is carried out on the theoretical failure probability of each SIF and the SIL of each SIF is determined based on the theoretical failure probability and the failure consequence level of each SIF, so accuracy of the SIL is improved.