In 2016，affected by multiple factors，the development of international security situation confronted some new issues and showed some new features and new trends with profound influence，which brought about new challenges to international security. Represented by Brexit and Donald Trump's being elected as President of the U.S.，populism began to rise in Europe and America，tremendously affecting the development of the world's politics and international security，and possibly reshaping the world political ecology. Major countries have maintained stability on the whole，yet their strategic gaming and deeper-level competition in the security field are becoming increasingly fierce，making the direction and prospect for the relationship among them full of uncertainties. Hot issues of regional security have taken different paths. Some have been mitigated while others have remained unchanged or even intensified，exerting negative influence on international security. Still a great threat to international security，terrorism is generally on the rise，turning towards more global，local，fragmented，and cyberspace-based models. As for China，the national security situation is generally stable. Guided by a comprehensive approach to national security，China has continued to promote theoretical and practical innovations in the field of national security，and achieved breakthroughs in national security strategy and legislation. The Chinese government has taken well-targeted measures and made positive progress in responding to risks in public health security，cyberspace security，nuclear power security，urban security，and the risks arising in the reform for better management of public markets and the trade in public resources. However，deficiencies still remain，awaiting further capacity building and system building.