The essay attempts to summarize Michael Halliday’s contribution to the theory of syntactic semantics according to the author’s understanding. Starting from the origin of his ideas, the essay then explains what syntactic semantics means and the concept of transitivity system and several processes such as material processes, behavioural processes and mental processes. Finally, Halliday’s new ideas are described-namely the micro perspective of one part of the functional linguistics. The essay attempts to summarize Michael Halliday’s contribution to the theory of syntactic semantics according to the author’s understanding. The beginning of the origin of his ideas, the essay then explains what syntactic semantics means and the concept of transitivity system and several processes such as material processes, behavioural processes and mental processes. Finally, Halliday’s new ideas are described-namely the micro perspective of one part of the functional linguistics.