On the basis of Halliday's framework of Systemic Functional Grammar(SFG),this paper attempts to make a critical analysis of Donald Trump's presidential inaugural speech,with respect to transitivity,modality,personal pronouns and transformation,so as to bring to light the speaker's political intention.Based on the qualitative and quantitative analyses,it is concluded that material process,existential process,passivization and first person pronoun are rather frequent in the speech,which aims to build a good government image and wins as much as support from the people.