运行环境（英语：Runtime environment）又称“运行时系统”（run-time system），指一种把半编译的运行码在目标机器上运行的环境。

运行环境是一种介乎编译器及直译器的运行方式。Java运行环境，称之为“Java Runtime Environment”（JRE）。一个由C#，Visual Basic .NET，C++.Net之类的语言写的进程运行于Microsoft Windows上的.NET Common Language Runtime（CLR）或Linux上的Mono。

A runtime system, also called run-time system, primarily implements portions of an execution model. This is in contrast to the runtime lifecycle phase of a program, during which the runtime system is in operation. Most languages have some form of runtime system, which implements control over the order in which work that was specified in terms of the language gets performed. Over the years, the meaning of the term 'runtime system' has been expanded to include nearly any behaviors that are dynamically determined during execution.