操作语义学是计算机科学中的一个概念，它是使得计算机进程在数学上更加严谨的一种手段。其它类似的手段包括提供形式语义学，包括公理语义学和指称语义。

一个计算机语言的操作语义描述一段合理的进程是怎样被理解为一系列计算机步骤的。这些步骤就是这个进程的意义。在函数编程语言中一段终结性的串行在最后一步的返回进程的值。（由于一个进程可能是非非决定的，一般来说一个进程能够有许多不同的计算步骤和许多不同的返回值。）

操作语义最早被用来定义Algol 68的语义。下面这句话引用修正的ALGOL 68报告：

一个使用严格语言编写的进程的意义是通过一个假设的计算机来执行该进程的组成部分时完成的行动来解释的。（Algol68，第二章）

Operational semantics are a category of formal programming language semantics in which certain desired properties of a program, such as correctness, safety or security, are verified by constructing proofs from logical statements about its execution and procedures, rather than by attaching mathematical meanings to its terms (denotational semantics). Operational semantics are classified in two categories: structural operational semantics (or small-step semantics) formally describe how the individual steps of a computation take place in a computer-based system. By opposition natural semantics (or big-step semantics) describe how the overall results of the executions are obtained. Other approaches to providing a formal semantics of programming languages include axiomatic semantics and denotational semantics.