分析了基于CCD相机激光光束宽度测量过程中引入的噪声特性，并给出了有效抑制噪声的方法，说明了在光束宽度计算过程中尤其采用4σ算法时，积分区域选取的意义及正确的选取方法，总结了影响基于CCD相机激光光束宽度精确测量的因素。通过实验，进一步验证了用4σ算法计算激光光束宽度时，特别是计算小光斑光束宽度时，积分区域限制的重要性；提出了积分区域最佳选取值为2倍的光束宽度；得出了如无噪声影响，CCD空间分辨率对基于4σ算法的光束宽度结果影响很小的结论，即采用4σ算法虽然光束宽度内仅有十几个甚至几个像素，仍可得到准确的光束宽度值；定量给出了高频随机噪声对基于4σ算法的光束宽度测量重复性的影响，以及提高测量结果精确度的方法；分析了基底噪声对基于4σ算法的光束宽度测量结果的影响程度，提出了正确的背景图像扣除方法以减少基底噪声的影响。

The noise characteristics existing in the laser beam width measurement based on CCD camera are analyzed, and the methods of effectively restraining noise are presented. The importance of the limitation of integration area for the 4σ beam width measurement, and the method to correctly select integration area are discussed. Factors affecting the accuracy of the laser beam width measurement with CCD camera are summarized. The analyses of experimental data prove that random noise and baseline offset have great effects on the small beam width with 4σ method, and the limitation of integration area for the 4σ beam width measurement is necessary. Furthermore, the experimental results show that the optimum integration area size is 2 times of the beam width; the CCD spatial resolution has little impact on the 4σ beam width measurement in the absence of noises, that is, a few pixel data can get the correct results. Besides, the effect of high frequency random noise on the 4σ beam width measurement repeatability and the methods to improve the meaurement accuracy are discussed; the effect of baseline error on the 4σ laser beam width measurement is analyzed, and the proper method of the background map subtraction is proposed to reduce the influence of noise.