预编译头（precompiled header）是进程设计时把头文档编译为中间格式（如目标文档），以节约在开发过程中编译器反复编译该头文档的开销。 C语言、C++语言、Objective C语言等都有类似的技术。

有的头文档包含了巨量的源代码（如著名的windows.h），或者使用模板编程时要生成巨大的头文档模板库（如Eigen math library与Boost C++ libraries)。为减少编译时间，某些编译器允许把头文档编译为某种中间形式称为预编译头（precompiled header），后续再编译源文档时就可以尽量直接使用这些预编译头。

In computer programming, a precompiled header is a (C or C++) header file that is compiled into an intermediate form that is faster to process for the compiler. Usage of precompiled headers may significantly reduce compilation time, especially when applied to large header files, header files that include many other header files, or header files that are included in many translation units.