针对长波红外系统中普遍存在的噪声大和信噪比低的问题，重点阐述三维噪声模型的理论分析方法，并设计了一套长波红外噪声测试系统。在不同积分时间下对不同温度的黑体连续采集图像数据，通过图像数据计算出三维噪声模型中噪声分量的数值，深入地分析了各噪声分量对系统信噪比的影响，发现长波红外系统的主导噪声为行列非均匀性所产生的噪声，空间噪声比时间噪声更为严重，成为限制系统信噪比的重要因素，为长波红外系统信噪比的提高提供了理论依据。

In view of the widespread problem of large noise and low signal-to-noise ratio in long wave infrared system, the analysis method of 3-D noise model theory was emphasized, and a set of long wave infrared noise measurement system was designed. With the imaging system, continuous acquisition of image data was completed from different temperature blackbody under different integration time. The influence of noise components on system signal-to-noise ratio was analyzed in-depth by values of noise components which were calculated by the data. The results present that the dominant noise of long wave infrared system is that row and column non-uniformity results in, and spatial noise is worse than temporal noise and becomes the key factor of restriction to system signal-to-noise ratio improvement. This work provides theory basis for improvement of signal-to-noise ratio of the long wave infrared system.