负回馈（英语：negative feedback），在**称作负回馈，又称负回授，是反馈的一种。是指系统的输出会影响系统的输入，在输出变动时，所造成的影响恰和原来变动的趋势相反；反之，就称为正回馈。另一种说法是系统在一个条件变化时，系统会作出抵抗该变化的行为。例如人的体温上升时会流汗，流汗会散热使体温下降，就是负反馈的一个例子，在自然界有许多系统有负反馈的特性。

在特定的条件下，负回馈会使系统趋于稳定，负反馈的研究是控制理论的核心问题。

Negative feedback occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances.

Whereas positive feedback tends to lead to instability via exponential growth, oscillation or chaotic behavior, negative feedback generally promotes stability. Negative feedback tends to promote a settling to equilibrium, and reduces the effects of perturbations. Negative feedback loops in which just the right amount of correction is applied with optimum timing can be very stable, accurate, and responsive.