本文认为跟单信用证交易涉及四种性质不同的法律关系即保证合同关系、委托合同关系、意定代理关系和票据法律关系。这四种法律关系由于跟单信用证所具有的国际法上的属性而相应地表现出不同于国内法上一般规定的特质。本文着重阐述了信用证保证的特点即直接的银行信用、完全的独立性和绝对的付款义务，并分析了信用证保证与一般保证和凭要求即付保证的区别，以及跟单信用证交易项下意定代理关系和票据法律关系的一些独特之处 This article considers that the four types of legal relations involving the contractual letter of credit transaction involve the contractual relationship, the contractual relationship, the agency relationship and the legal relationship of notes. These four types of legal relations, due to the attributes of international law enjoyed by documentary letters of credit, exhibit traits that differ from the general provisions of national law. This article emphatically expounds the characteristics of L / C guarantee, that is, direct bank credit, complete independence and absolute payment obligation, and analyzes the difference between L / C guarantee and general guarantee and on demand payment guarantee, Something special about the relationship between agent and negotiable instrument