Poisson分布（法语：loi de Poisson，英语：Poisson distribution），译名有泊松分布、普阿松分布、卜瓦松分布、布瓦松分布、布阿松分布、波以松分布、卜氏分配等，又称卜瓦松小数法则（Poisson law of small numbers），是一种统计与概率学里常见到的离散机率分布，由法国数学家西莫恩·德尼·泊松（Siméon-Denis Poisson）在1838年时发表。

泊松分布适合于描述单位时间内随机事件发生的次数的概率分布。如某一服务设施在一定时间内受到的服务请求的次数，电话交换机接到调用的次数、汽车站台的候客人数、机器出现的故障数、自然灾害发生的次数、DNA串行的变异数、放射性原子核的衰变数等等。

In probability theory and statistics, the Poisson distribution (French pronunciation [pwasɔ̃]; in English usually /ˈpwɑːsɒn/), named after French mathematician Siméon Denis Poisson, is a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time and/or space if these events occur with a known average rate and independently of the time since the last event. The Poisson distribution can also be used for the number of events in other specified intervals such as distance, area or volume.