This paper aims to describe the theme of English clause in terms of systemic grammar. For this I analyze the three subaereas of subject theme and the four subareas of nonsubject theme in the form of features. Each of the seven feature sets of the seven thematic subareas is described in the systemic model. Finally All of the subsystems are described in the framework of the system network in order to show the potential of options of thematic English clause available in a certain situation.