液压缸（英语：Hydraulic cylinder)也称为线性的油压马达，是一种机械致动器，用来从单向的行程得到单向的力。许多应用都会使用到液压缸，尤其是在工程作业车辆中，像挖土机就利用液压缸来控制铲子以及机械手臂的动作。

液压缸的构造主要有三：缸桶、活塞以及活塞杆。

A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment (engineering vehicles), manufacturing machinery, and civil engineering.