奈奎斯特图（英语：Nyquist plot）是对于一个连续时间的线性非时变系统，将其频率响应的增益及相位以极座标的方式在复平面中绘出，常在控制系统或信号处理中使用，可以用来判断一个有反馈的系统是否稳定。奈奎斯特图的命名是来自贝尔实验室的电子工程师哈里·奈奎斯特（Harry Nyquist）。

奈奎斯特图上每一点都是对应一特定频率下的频率响应，该点相对于原点的角度表示相位，而和原点之间的距离表示增益，因此奈奎斯特图将振幅及相位的波德图综合在一张图中。

一般的系统有低通滤波器的特性，高频时的频率响应会衰减，增益降低，因此在奈奎斯特图中会出现在较靠近原点的区域。

A Nyquist plot is a parametric plot of a frequency response used in automatic control and signal processing. The most common use of Nyquist plots is for assessing the stability of a system with feedback. In Cartesian coordinates, the real part of the transfer function is plotted on the X axis. The imaginary part is plotted on the Y axis. The frequency is swept as a parameter, resulting in a plot per frequency. Alternatively, in polar coordinates, the gain of the transfer function is plotted as the radial coordinate, while the phase of the transfer function is plotted as the angular coordinate. The Nyquist plot is named after Harry Nyquist, a former engineer at Bell Laboratories.