根据 Dictionary.com, person 的 plural 可以是 persons 或 people，但是现代英语都是使用 people 的。
There is understandable confusion about the plural of this word. Is it persons or people? Person —like other regular English nouns—constructs its grammatical plural by adding -s, forming persons. This has been so since person came into Middle English in the late twelfth century. But as far back as the fourteenth century, some writers, including the poet Chaucer, were using an entirely different word— people, not persons —as the functional plural of person. And today, people seems more natural, especially in casual, informal conversation or writing.
Using people as a plural of person has not always been free of controversy. From the mid nineteenth to the late twentieth century, the use of people instead of persons was hotly contested; and among some news publications, book publishers, and writers of usage books, it was expressly forbidden. To quell the fires of the argument, some usage authorities attempted to regulate use of the two forms—recommending persons when counting a small, specific number of individuals ( Three persons were injured in the accident ) and people when referring to a large, round, or uncountable number ( More than two thousand people bought tickets on the first day; People crowded around the exhibit, blocking it from view ).
But efforts to impose such precise rules in language usually fail. This rule does not appear in currently popular style manuals, and if such a rule still exists in anyone's mind, it is mainly ignored. People is the plural form that most people are most comfortable with most of the time. Persons seems excessively formal and stilted in ordinary conversation or casual writing. One would probably not say, “How many persons came to your birthday party?” In legal or formal contexts, however, persons is often the form of choice ( The police are looking for any person or persons who may have witnessed the crime; Occupancy by more than 75 persons is prohibited by the fire marshal ). In addition, persons is often used when we pluralize person in a set phrase ( missing persons; persons of interest ). Otherwise, the modern consensus is that people is the preferred plural. Persons is not wrong, but it is increasingly rare.