应急计划（或B计划），是指政府或企业为应对可能发生的突发事件而事先制订的计划或方案。

当原定的计划出现问题时，应急计划便大派用场。

For the play of this title, see The Contingency Plan.

A contingency plan is a plan devised for an outcome other than in the usual (expected) plan.

It is often used for risk management when an exceptional risk that, though unlikely, would have catastrophic consequences. Contingency plans are often devised by governments or businesses. For example, suppose many employees of a company are traveling together on an aircraft which crashes, killing all aboard. The company could be severely strained or even ruined by such a loss. Accordingly, many companies have procedures to follow in the event of such a disaster. The plan may also include standing policies to mitigate a disaster's potential impact, such as requiring employees to travel separately or limiting the number of employees on any one aircraft.