Within the increasing cooperation and interactions between China and Russia, some analysts think that there may be an emerging alliance between China and Russia. Especially, Russian President Vladimir Putin’s invasion of Ukraine and annexation of Crimea was met with heavy economic sanctions from Europe and the United States, weakening Russia’s ties with the West and leaving the Kremlin eager to strengthen ties with China. Moreover, in the beginning of 2015, Russia invited China to participate the Russian military parade in honour of a victory in WW II, and the two countries also held the joint military exercise at Mediterranean...all these imply that the relations between China and Russia are trend to form an alliance. But the question is that China is close to Russia, they have geographic proximity factor which makes each other lack of political trusts and perpetual interests for forming alliance, and more threats may come from the neighbouring country. Besides, It’s impossible for the second-tier great powers to form an alliance under the unipolar world except for a large change in international society. So, analysis based on the balance of threat theory, the conclusion is strategic partnership is still the most appropriate form between China and Russian and it is the best choice for the two countries nowadays, but the Sino-Russian relations are always change along with the different independent variables, we may should take the external threats and security considerations into account.