(1)μ is the position parameter of normal distribution, which describes the centralized trend position of normal distribution. Normal distribution takes X=μ as the symmetry axis, and the left and right sides are completely symmetrical. The mean, median and mode of normal distribution are the same, all equal to μ. (2)σ describes the dispersion degree of normal distribution data. The larger σ is, the more dispersed the data distribution is, and the smaller σ is, the more concentrated the data distribution is. Also known as the shape parameter of normal distribution, the greater σ, the flatter the curve; Conversely, the smaller σ is, the thinner the curve is.