等同原则（英语：Doctrine of Equivalents），一个法律原则，广泛存在于多数国家的专利系统内。即使某一方侵权产品或方法并没有正好落入某专利的权利要求的字面范围内，但却等同于权利要求所保护的发明时，等同原则允许法庭判决该方侵犯他人专利。美国法官勒尼德·汉德曾经这样描述过等同原则的目的：“....减少慷慨之逻辑，并防止侵权者盗用发明。”（“皇家打字机公司”一案，Royal Typewriter Co.v.Remington Rand,Inc., 168 F.2d 691, 692 (2d Cir. 1948）。

The doctrine of equivalents is a legal rule in most of the world's patent systems that allows a court to hold a party liable for patent infringement even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed invention. U.S. judge Learned Hand has described its purpose as being "to temper unsparing logic and prevent an infringer from stealing the benefit of the invention".