Although recording facts and events of human society is one of the objectives of the social documentary photography, a social documentary photographer does not tend to provide merely an apparent picture from reality and a report-type factuality, but selects and composes varied elements and facts of human community to frame a piece of social reality in a given moment of time, to produce a photograph that invites addressee to watch, think, comprehend and judge. It can even stimulate addressee’s response to the subject. In fact, the social documentary photographs may variably influence on addressees because of their social nature, and they may like language, represent different functions as well. Thus, the objective of this paper is to examine and analyze the functions of such photographs on the basis of the linguistic functions of the Jacobson’s communicative theory. The question is what are the main elements of social documentary photographs that provide them with different functions? The methodology of the study is descriptive – analytical and comparative. The study results indicate that in every social documentary photograph, we would face one of the dominated functions: referring, emotional, encouraging and artistic. In other words, a social documentary photographer may provide only information around a subject (a referring function), express his insight and sense for an object (emotional function), urge one to react by stimulating one’s sensibility and thought (encouraging function), or else, create a visual passion in addressee by highlighting apparent construct of a photograph (artistic function). Nonetheless, frame and shooting moment remain as major elements for having these functions.