DLT supply a new way and a set of solution to achieve trust through collective decision-making and maintaining in a decentralized way. The architecture and key technologies can achieve some security features. Thus the platform and service system based on DLT naturally have the capability of these security protection. On the other hand, DLT still has some limitations and security threats which vary according to deployment model and service. In brief, security is not only one motivation of applying DLT but also what should be considered to enhance. This Recommendation provides security analysis for developing, operating or using DLT and to support security evaluation for the platform or service system based on DLT. It researches security capabilities achieved by DLT itself and also list security threats to DLT.