US national security review becomes the biggest legal risks faced by Chinese enterprises in their overseas mergers and acquisitions．There are trends in the legal practice of national security review in recent years: expansion of the national security concept, increase of political considerations, flexibility of procedure and lack of transparency．During the SinoUS Bilateral Investment Treaty negotiations, China pays close attention to the US national security review. The “essential security” exception clause may play a positive role in solving this problem. Therefore, to make a proper arrangement regarding national security review in the “essential security” exception clause in the future SinoUS BIT is of great significance to reducing the conflictions in overseas mergers and acquisitions caused by US national security review．