本文阐明二维正态随机变量的圆周概率差等一些基本概念,推导出圆周概率偏差的基本公式。同时研究了圆周概率的三种实用计算方法,并作了比较,及举例。最后简论了二维随机变量合成一维随机变量;和一维随机变量分解为二维时所采用的方法。 This paper clarifies some basic concepts such as the difference of the circumferential probabilities of two-dimensional normal random variables, and deduces the basic formula of the probabilistic deviation of the circumference. At the same time, three practical methods for calculating the probability of circumference are studied and compared. Finally, we briefly discuss the synthesis of one-dimensional random variables by two-dimensional random variables and the methods used when one-dimensional random variables are decomposed into two dimensions.