PDCA（Plan-Do-Check-Action的简称）循环是品质管理循环，针对品质工作按规划、运行、查核与行动来进行活动，以确保可靠度目标之达成，并进而促使品质持续改善。由美国学者爱德华兹·戴明提出。这个四部的循环一般用来提高产品质量和改善产品生产过程。这个过程循环也被人熟知为：Plan-Do-Study-Act(PDSA)，戴明圆环（Deming cicle/cycle/wheel）或者休哈特圆环。另一个不同的版本是OPDCA，加入了O（observation观察），有些说法是说获得当前的状况。

PDCA (plan–do–check–act or plan–do–check–adjust) is an iterative four-step management method used in business for the control and continuous improvement of processes and products. It is also known as the Deming circle/cycle/wheel, Shewhart cycle, control circle/cycle, or plan–do–study–act (PDSA). Another version of this PDCA cycle is OPDCA. The added "O" stands for observation or as some versions say "Grasp the current condition." This emphasis on observation and current condition has currency with Lean manufacturing/Toyota Production System literature.