根据随机型概率分布（Ｐｏｉｓｓｏｎ分布）中，方差（ｖ）与均值（ｍ）相等的性质，提出一个新的种群聚集度指标，，＝ｍ／ｎ＋ｍ。指标不仅可用来判断昆虫种群的空间分布型，而且ｃ’与ｍ之间存在着线性关系。据此，提出了“ｃ－ｍ回归模型：ｃ＝ａ＋ｂｍ。当ｃ’与ｍ线性相关显著时，ａ、ｂ的不同组合型式就揭示了种群不同的空间分布型的信息。根据ｃ－ｍ模型，推导了序贯抽样方程和最大抽样数量的确定公式。 According to the property that the variance (v) is equal to the mean (m) in the random probability distribution (Poisson distribution), a new index of population clustering degree is proposed, = m / n + m. The index can not only be used to determine the spatial distribution of insect populations, but also has a linear relationship between c ’and m. Therefore, the "c-m regression model is proposed: c = a + bm. When c ’is linearly related to m, different combinations of a and b reveal the spatial distribution of different populations. According to the c-m model , The formula of sequential sampling equation and the maximum sampling number are deduced.