厘米-克-秒单位制或厘米-克-秒系统（英文：centimetre-gram-second system，故常简称CGS制）是一种物理单位的系统制度，分别以厘米、克及秒为长度、质量及时间的基本单位。

在力学单位方面厘米-克-秒单位制是一致的，但在电学单位方面则有几种变体。此单位系统后来被MKS制取代，也就是米-千克-秒系统（meter-kilogram-second system），而其又被国际单位制（SI system）所取代；国际单位制具有MKS制的三个基本单位，再加上安培、莫耳、烛光及凯氏温标，有许多任务程及科学领域只使用国际单位制，不过仍有一些领域常使用厘米-克-秒单位制。

The 'centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways of extending the CGS system to cover electromagnetism.