压水反应堆（Pressurized Water Reactor，缩写为PWR）是美国贝蒂斯原子能实验室开发成功的一种轻水核反应堆。所有的压水反应堆利用普通水作为冷却剂和中子慢化剂。

压水堆原本设计用作核潜艇的核能船舶用推进，并被用于在码头市核电站（Shippingport Atomic Power Station）第二个商业核电厂原始设计中。

目前在美国运行的压水反应堆被认为是第二代核反应堆。俄罗斯VVER反应堆类似于美国压水反应堆。法国运行的许多压水反应堆生产法国的大部分电力。

Pressurized water reactors (PWRs) constitute the large majority of all western nuclear power plants (excepting the United Kingdom) and are one of three types of light water reactor (LWR), the other types being boiling water reactors (BWRs) and supercritical water reactors (SCWRs). In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy generated by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator. In contrast to a boiling water reactor, pressure in the primary coolant loop prevents the water from boiling within the reactor. All LWRs use ordinary water as both coolant and neutron moderator.