Covering a vast area and boasting a long land borderline，China’s northwestern region is the bond and bridge for China’s exchanges and cooperation with its neighbours. The reshaping and reconfiguration of international political and economic structure is changing the security environment of China’s northwestern border，giving rise to new issues relating to the security environment of China’s contemporary northwestern border. These issues are demonstrated in military security，strategic security and unconventional security，with different features but equally serious implications. The factors affecting the contemporary security environment of China’s northwestern border mainly come from historical，geopolitical，economic，cultural sectors and conflict of national interest. No matter how they change and come into play，we must ensure the contemporary security of China’s northwestern border，which is the bottom line of national interest and serves as a precondition for the construction of harmonious and stable Silk Road Economic Belt.